A leading Irish metals refinery is part of an international aluminium supply chain that appears to conclude with shipments to arms producers feeding the Kremlin’s war machine in Ukraine, leaked records and public data suggests.

Trading records show that shipments to Russian smelters from Aughinish Alumina, which is located on the Shannon estuary in the west of Ireland and has been owned by the Russian aluminium group Rusal since 2006, have increased sharply since the invasion of Ukraine in 2022.

Ireland exported $243m (£180m) of alumina to Russia in 2022, according to the Observatory of Economic Complexity (OEC), a data analytics website,and this rose by 55% to $376m in 2024. Aughinish is Ireland’s only producer of alumina and the largest producer of the main raw material for making aluminium in Europe, according to a 2021 report by the accounting group KPMG.

The rising trade with Russia does not appear to breach sanctions law and can be interrogated via publicly available shipping records.

However, analysis of further data – leaked to the Russian investigative website iStories and shared with international media groups including the Guardian, the Organized Crime and Corruption Reporting Project (OCCRP) and the Irish Times – raises fresh questions about the EU’s ability to prevent Russian arms manufacturers from utilising the trading bloc’s raw materials.

The records also appear to misalign with previous reassurance from the Irish government. In 2022, Ireland’s then public expenditure minister of state, Patrick O’Donovan, told the country’s parliament that the plant “is not in any way connected to a war machine”.

Having been presented with findings from the new data, Aughinish representatives did not comment when asked by the Guardian and the OCCRP how the facility ensured products had not contributed to Russian assaults on Ukraine. O’Donovan did not comment.

Prof Aristides Matopoulos, a defence supply chains specialist from Cranfield University, said: “Defence supply chains are inherently multi-tier and cross-border, which creates structural gaps that can render sanctions architecture not fully fit for purpose.

“When you trace the supply chain – from bauxite mine to alumina refinery, to smelter, to trading intermediary, and ultimately to a weapons producer – it becomes clear that every node in the chain could appear fully compliant while still enabling strategic materials to reach sanctioned end users. This is because end-use tracing of commodities such as alumina across opaque supply chains, while technically possible, remains highly challenging in practice.”

Rusal’s shipments of alumina between its sites in Ireland and Russia are legal as the EU has not placed sanctions on the commodity – even though the resultant aluminium has wide military uses and about a quarter of Rusal’s shares are owned indirectly by the under-sanctions Russian metals tycoon Oleg Deripaska.

The oligarch has personally been placed under sanctions by the UK, the EU and the US, but in 2019 the US lifted embargos imposed on Rusal after Deripaska relinquished his controlling interest in the aluminium group’s largest shareholder, EN+. Rusal also avoided sanctions in the EU and the UK after Russia’s invasion of Ukraine.

A spokesperson for Aughinish said: “We operate in strict compliance with all applicable EU laws, including sanctions, export control measures and trade regulations. We uphold a strong commitment to lawful and responsible business practices and continuously monitor regulatory developments to ensure the highest standards of compliance. The company implemented a robust sanctions compliance and due diligence framework covering its entire supply chain.”

The Aughinish refinery was built in the 1970s by the aluminium giant Alcan as Ireland prepared to join what was then the European Economic Community (EEC). The facility was acquired by the commodity trader Glencore, which then joined forces with the Russian aluminium groups Rusal and SUAL in 2006 to create the “world’s biggest aluminium producer”.

The plant is one of the largest employers in the west of Ireland, and was reported as employing about 900 staff and supplying about 30% of the EU’s alumina, for use in everything from medical devices to mobile phones, according to the KPMG report.

Rusal’s refinery in Aughinish extracts aluminium oxide – otherwise known as alumina – from the sedimentary rock bauxite. The alumina is then shipped to several Russian sister companies in the wider Rusal group, including a huge smelter at Krasnoyarsk, the second largest city in Siberia, where it is converted into aluminium.

Analysis of public records suggests that almost 500,000 tonnes of alumina, worth about $200m, was exported from Aughinish to Krasnoyarsk in 2024, which accounted for around two-thirds of the aluminium oxide imported into Russia by that Rusal smelter that year. The quantities of Irish alumina shipped appear to satisfy about 25% of the Siberian facility’s annual aluminium output of 1m tonnes.

During the same period, aluminium produced at Krasnoyarsk was sold through Rusal’s in-house trading firm, OK Rusal TD, to a third-party trading company called Aluminium Sales Company (ASK), the leaked records suggest, with ASK seeming to have paid Rusal about $300m in 2024.

The data also sets out apparent connections between ASK and Rusal including overlaps in property and financing: ASK shares addresses with Rusal branches in Russian cities such as Moscow, Volgograd and Bratsk, while it also looks to have received loans from the aluminium group.

Meanwhile, ASK customers include dozens of under-sanctions arms companies that have produced missiles, explosives and long-range bombers that have been used in attacks on Ukraine. For example, during 2024, ASK’s largest client appeared to be the Sverdlov plant in the Russian town of Dzerzhinsk, about 250 miles to the east of Moscow, which manufactures missile casings and explosives and was said by Ukrainian forces to have been targeted by its forces in October.

The Sverdlov plant is Russia’s only significant maker of the high explosives RDX and HMX, according to a Ukrainian intelligence official and the Council of the European Union, which placed the company under sanctions in 2023.

In total, companies that manufacture weapons paid ASK $337m for aluminium under Russian state defence contracts from February 2022 and April 2025, according to the leaked documents.

Spokespeople for ASK, Rusal, EN+ and Deripaska did not respond to invitations to comment on the analysis of the data when approached by the Guardian – including questions on whether the use of an intermediary trading company was a method of avoiding sanctions.

Rusal’s Aughinish’s spokesperson said: “We particularly underline the fact that both alumina and aluminium are an internationally recognised basic commodity, the very nature of which means they serve broad general purpose societal needs and vital for countless civilian industries.

“We believe, that any attempt to state the contrary is flawed and seeks to create a biased narrative. Especially singling out one company for criticism in this manner discredits legitimate and vital business operations supporting thousands of workers, contractors and families, bringing economic value.”

A spokesperson for Ireland’s department of enterprise, tourism and employment said: “The general principle of EU sanctions on Russia is that their imposition does not have a greater impact on a European member state than on Russia itself. The Aughinish plant is not subject to sanctions by the EU, nor has it been proposed by the EU for sanctions. Alumina is also not a sanctioned good therefore its export to other countries, including Russia, is not restricted. The Irish authorities are committed to ensuring all sanctions are observed once they take force.

“Ireland remains unequivocal in its continuing support for Ukraine in light of Russia’s unjustified invasion.”