The UK government has been forced to delay the introduction of import checks by six months, in a U-turn in post-Brexit policy, because a network of 30 border posts being built to process incoming goods would not have been ready on time.

Exports to the EU from Britain have been subject to controls since 1 January, but the government decided to opt for a phased approach on EU imports to give hauliers and business more time to adapt.

Checks were due to be introduced in stages from 1 April and from 1 July, but in recent days traders and ports have said they are not ready and that the introduction of processes as originally planned could lead to empty supermarket shelves.

Michael Gove, the minister for the Cabinet Office, told the House of Commons on Thursday that the government had responded to businesses’ requests for more time and announced what he called a “revised timetable”.

Gove blamed the need for delays on the pandemic, telling MPs the previous timetable was “based on the impacts of the first wave of Covid” but that the government had reviewed deadlines because the disruption had been wider and longer-lasting than expected.

Most import checks have now been pushed back to 1 January 2022, meaning Britain will begin these processes a year later than the EU.

Andrew Opie, the director of food and sustainability at the British Retail Consortium, a lobby group, said the postponement had come “in the nick of time”. He said it would “ultimately reduce the impact on consumers from 1 April who might otherwise have seen empty shelves for some products”.

Opie added: “Until the infrastructure is in place, with IT systems ready and established processes for checks and paperwork, it would be foolhardy to introduce full requirements for export health certificate documentation, pre-notification of imports, physical checks and more.”

British customs were due to begin controlling imports of animal products, live animals and plants and products from 1 April, including food considered high-risk such as mince and sausages. The checks, known as sanitary and phytosanitary (SPS) controls, require consignments to have the correct documentation and import and health certificates signed by vets on arrival in Britain.

These SPS checks along with customs inspections were expected to take place from 1 July at new designated border control posts (BCPs) on goods entering by sea, road or air.

However, in recent weeks a string of British ports had said the facilities would not be ready in time for the July deadline, partly as a result of complications with the government’s funding of the new infrastructure. This week the British Ports Association, an industry body, wrote to the government to urge it to extend the deadline.

In addition, several of the inland facilities being built by the government at locations where there is not enough space available for a border control post directly next to the port are running behind schedule.

The White Cliffs inland site in Kent, where goods arriving at Dover will be checked, is described as still being a “muddy field”. In addition, the locations of the two inland sites in Wales that are being developed by the Welsh and UK governments have not yet been announced.

Physical SPS checks on animal products, as well as foods and plants considered high risk will not take place until 1 January. From this date these checks will take place at designated border control posts rather than at their destination, as is currently the case.

Checks on live animals and low-risk plants will only take place from March 2022 at BCPs.

In addition, traders will be able to continue submitting deferred customs declarations, whereby paperwork can be provided up to six months after goods have been imported, until the start of 2022.

There have also been severe teething problems in the implementation of the Northern Ireland protocol and new trading rules with the EU.

The EU is preparing to launch legal action within days after the government last week announced it was unilaterally extending a series of “grace periods” to allow businesses in Northern Ireland more time to adapt to post-Brexit rules.

Speaking to journalists on Thursday, the EU’s ambassador to the UK, João Vale de Almeida, said both sides should “give up on trying to score points” and work to rebuild trust.

It is understood Vale de Almeida has not yet met David Frost, the cabinet minister in charge of UK relations with the EU and the former trade negotiator. EU sources are understood to feel alarm at rumours circulating that the UK government has motive to make the Northern Ireland protocol inoperable in order to force a renegotiation – a situation tha Brussels would face down in the strongest possible terms.