The UK Treasury has a “limited grasp” of concerns linked to the booming shadow banking sector and may not be prepared for risks the unregulated industry poses to financial stability, peers have said.

While a lack of data makes it hard to say whether the $16tn (£12tn) non-bank financial sector could bring the wider financial system to its knees, officials do not seem to be alive to the potential risks, according to a Lords financial services regulation committee report.

It says the department’s evidence “demonstrated a limited grasp of the concerns raised during this inquiry, which suggested passivity in the face of potential risks to the UK’s financial stability arising from the growth of private markets”.

That raises concerns given the Treasury’s responsibility for “ensuring overall financial stability so that the taxpayer does not serve as a backstop to the financial system”.

The report says the UK could be one of the first countries to feel the fallout from a downturn in the US-dominated shadow banking sector, which has quadrupled in value from $4tn in 2008.

The largely unregulated industry includes private equity houses, which acquire businesses, and private credit firms that compete with regulated banks to issue loans to businesses.

The sector is dominated by US firms but is entangled with mainstream insurers and regulated high street banks, including in the UK, which invest and lend money to the industry.

The International Monetary Fund said last year that a downturn in the private credit sector could have ripple effects across the financial system, potentially destabilising traditional banks that issue loans to the shadow banking sector.

The committee report says: “The UK’s position as a global financial centre means it will be the first to experience the opportunities and risks arising from this growth, particularly in US private markets.”

The Bank of England governor, Andrew Bailey, told the Lords inquiry in October that he had concerns after the collapse of two US auto firms that borrowed money from private markets. The cases raised questions about weak lending standards, with Bailey saying there were worrying echoes of the sub-prime mortgage crisis that kicked off the financial crisis.

The Bank is about to launch a private credit industry stress test that will map out potential risks linked to the sector’s growth, including whether it could end up amplifying financial and economic shocks

The committee’s chair, Michael Forsyth, who served in John Major’s government, said: “The Bank of England, the Financial Conduct Authority and the Prudential Regulation Authority are right to be vigilant and to monitor the dramatic growth of private markets and the implications for financial stability.”

A Treasury spokesperson said: “We have worked together with the regulators to significantly increase our focus on non-banks sectors in recent years and have a robust, flexible framework to protect financial stability.” They added that the Treasury would respond to the report in due course.