MPs have cast doubt over the UK government’s readiness for post-Brexit border control checks, which are due to come in next week, arguing that a scaling back of its plans appeared to represent a sixth delay to their long-awaited introduction.

The environment, food and rural affairs select committee (EFRA) has written to the government demanding clarity over the exact nature of the physical inspections on plant and food products, after it emerged these may be significantly scaled back due to fears of delays at the border.

On Tuesday, the government is scheduled to begin checks on medium and high-risk plant and animal imports from the EU, as part of its Border Target Operating Model (BTOM) plan.

However, the Financial Times reported last week that large parts of the risk management system for all commodity groups would not initially be switched on, after concerns within government that the border systems would not be fully ready.

The government insisted that checks would begin but said some would be delayed, with inspectors focusing on the highest risk products before scaling up to a more comprehensive regime in the future.

Robert Goodwill, the chair of the EFRA committee, demanded clarity from the government over what the latest delays entailed and details on what a graduated approach to the sanitary and phytosanitary (SPS) checks would look like in practice.

In a letter to the environment secretary, Steve Barclay, Goodwill said it was clear that ports and businesses were facing further uncertainty and were “confused and frustrated” over the delivery of these essential border controls.

He said: “There is broad consensus that a clearly communicated, phased implementation of SPS checks with distinct, achievable milestones is a strategic and pragmatic approach to change.

“We are concerned that your approach, if as reported, has resulted from poor planning and delivery of the model.”

Goodwill added: “We are concerned that this is a sixth delay to the implementation of SPS import checks in all but name.”

Physical checks at the border were first scheduled to be introduced in July 2021 but were pushed back as several border control posts were unfinished. There have been four subsequent delays, with the last one taking place in August 2023.

Last week, trade bodies described the border system as being in “complete disarray” after the latest delay to checks emerged, with some warning that the confusion around the government’s plans made it difficult for businesses to plan.

Businesses have repeatedly complained about being left in the dark over aspects of the government’s border plans. This includes delays to publishing crucial details about how much it will cost businesses to have plant and animal goods coming through the Port of Dover and Channel tunnel.

Despite a public consultation running last summer, and details being promised before the end of 2023, the specifics of the common user charge were only published earlier this month, 27 days before the checks were due to come in.

Ports have also complained that they have not received crucial information from the Department for Environment, Food and Rural Affairs (Defra) about inspector staffing arrangements and opening hours.

The letter from the committee pointed to these as examples of the government’s “inconsistent messaging”, and also questioned why the committee had not been informed of any changes to the government’s approach.

Goodwill wrote: “It is essential that Defra urgently takes steps to communicate the changed arrangements to businesses and the public to build confidence in our incoming border controls and reduce disruption.”

The committee has demanded details on the percentage of goods that the government intends to check by next Tuesday, as well as monthly updates on the progress of the inspections regime.

A government spokesperson said: “Taking a pragmatic approach to introducing our new border checks minimises disruption, protects our biosecurity and benefits everyone – especially traders.

“There has been extensive engagement with businesses over the past year – with our approach welcomed by several trade associations and port authorities.

“We are confident we have sufficient capacity and capability across all points of entry to handle the volume and type of expected checks.”