Businesses have described Britain’s Brexit border plans as being in “complete disarray” after it emerged the introduction of some checks on EU imports will be delayed.

Post-Brexit border rules, due to come into force on 30 April, will require many meat, dairy and plant products from the EU to be physically checked at government border control posts (BCPs).

But trade bodies have said fresh confusion about when the checks would begin were “incredibly challenging” for business planning, while others said serious questions remained about the government’s readiness for the regime.

Under the rules, medium- and high-risk products, which include meat and dairy products, as well as most plants, could be subject to checks at the borders as part of a move to enhance the UK’s biosecurity.

The Financial Times reported that the government would not “turn on” the checks on 30 April in an attempt to avert delays because border systems were not fully ready.

However, the government insisted the checks would be commencing on 30 April but indicated they would be focusing on higher-risk products and scaling up checks on other products in a “sensible and controlled way”.

The Guardian understands this will mean the government will focus the checks on the highest-risk products across high and medium bands, and then slowly build up to full checks. The government has yet to give a timeline on this but said it would take a “pragmatic approach”.

There have already been five previous delays to the implementation of the checks, which were initially set to come in in July 2021.

Phil Pluck, the chief executive of the Cold Chain Federation (CCF), said: “The ongoing confusion about how and when new checks will be introduced makes these preparations incredibly challenging.

“A phased approach is the right one but businesses urgently need clear information about what exactly these phases will include, and a definitive timeline.”

Martin McTague, the chair of the Federation of Small Businesses, said the system was in “complete disarray” and businesses were having to “decode messy and unclear messages” from Whitehall over whether they would face checks.

In January, the first phase of the border target operating model was introduced, with medium- and high-risk goods having to secure plant health and vet sign-offs before they could be exported to the UK.

Nan Jones, the technical policy manager at the British Meat Processors Association, said it was aware importers were making a high rate of mistakes in the new paperwork, which was causing issues with the government’s IT system at the border.

She said: “Currently there is no consequence for this error but once the new border controls come into force, these errors will result in consignments being directed to a BCP for an inspection.

“This could result in UK border posts being overwhelmed with extra work they are not equipped to process.”

Despite being just 11 days away from implementation, businesses have said there are gaping holes in the government’s regime, which are affecting their planning.

Delays to the government publishing its charges for goods coming through Dover has meant a number of private BCPs at ports across the country have yet to publish their rates for importers.

It has also emerged that the government’s Sevington BCP in Kent, which will process all Dover and Folkestone goods, has yet to receive formal designation that will allow it to carry out the checks.

To achieve designation, BCPs must meet a number of requirements, including complying with biosecurity protocols, having the correct equipment and staff, and being suitable for the volume of goods coming through.

Tom Southall, the executive director of the CCF, said the government had been telling it for months that this designation delay was down to a few snags but it would be ready. He added: “That this still hasn’t happened 11 days out is pretty incredible.”

Marco Forgione, the director general of the Institute of Export and International Trade, said: “Sevington hasn’t been approved, we’re still not sure yet what the full charging regime is going to be in most private BCPs […] there’s still a lot of work that needs to be done and we’re 11 days out.

“Businesses in the UK are unclear, businesses in the EU are even more uncertain.”

A UK government spokesperson said: “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.”