Brussels has warned it is not giving Boris Johnson’s Government a “blank cheque” after agreeing that chilled meats can continue being shipped to Northern Ireland for another three months.

The deal avoids a trade dispute – dubbed a “sausage war” – by delaying the ban until September 30 while efforts continue to find a lasting solution.

But European Commission vice-president Maros Sefcovic said the extension, agreed on the day current arrangements were due to expire, came with strict conditions.

He warned that “this continuous rolling-over of the grace period” does not give “predictability and stability” to businesses in Northern Ireland.

The UK had threatened to unilaterally extend the grace period to maintain the supply of sausages from Great Britain to Northern Ireland, in defiance of Brussels’ rules, which could have triggered retaliatory action from the EU.

The agreement – along with an EU promise to rewrite its rules to ensure medicines can continue being sent to Northern Ireland – showed there had been progress in discussions between the two sides.

The potential prohibition on chilled meats from Great Britain is one result of Brexit’s contentious Northern Ireland Protocol, which has created a series of economic barriers on Irish Sea trade.

The protocol is aimed at avoiding a hard border with Ireland by effectively keeping Northern Ireland in the EU’s single market for goods.

Shipments of chilled meats from third countries into the single market are generally banned – a prohibition which will eventually cover the rest of the UK unless a lasting solution is found.

Brexit minister Lord Frost has repeatedly complained about the implementation of the protocol, which was part of the deal negotiated by him and signed by Boris Johnson.

“We are pleased we have been able to agree a sensible extension on chilled meats moving from Great Britain to Northern Ireland – one that does not require rules in the rest of the UK to align with future changes in EU agrifood rules,” he said,

“This is a positive first step but we still need to agree a permanent solution – Northern Ireland is an integral part of the United Kingdom and its consumers should be able to enjoy products they have bought from Great Britain for years.”

He said the protocol “needs to be operated in a pragmatic and a proportionate way if it’s to be sustainable”.

“At the moment, it’s being operated in a legally purist way that is causing a very large number of problems of which the chilled meats issue is only one.”

Mr Sefcovic said: “We are not issuing a blank cheque. This solution is of temporary nature in which strong conditions are attached.”

But he insisted the deal was an “unquestionable response to those in the UK suggesting the EU is inflexible or too legalistic” – an apparent reference to Lord Frost and Mr Johnson.

He told reporters in Brussels the UK and EU had agreed solutions to a number of other issues, including the supply of medicines, waiving the insurance green card and the movement of livestock.

On the issue of medicines “we have completely turned our rules upside down and inside out to find the solid solution on outstanding challenge”, he said.

He suggested a lasting solution to the issue of checks on plant and animal products entering Northern Ireland – sanitary and phytosanitary (SPS) measures – would be a Swiss-style veterinary agreement.

But the UK has rejected anything that would require it to follow Brussels’ rules, with Mr Sefcovic saying the UK had chosen to pursue a “super clean Brexit approach” which meant there would have to be some barriers to protect public health

To secure the extension the UK agreed to maintain existing rules relating to meat products, but will not be forced to make changes if Brussels varies its legislation.

The products from Great Britain will only be sold in supermarkets, will be accompanied by official certificates and will bear a label making clear they are for sale only in the UK – meaning they cannot be allowed to cross into Ireland and the EU’s single market.

Under the deal, the UK will endeavour to introduce product-level labelling “as soon as is practicable”.

The extension was welcomed by business leaders, but they called for permanent agreements on issues around food supplies.

Baroness Jenny Chapman, Lord Frost’s opposite number for Labour, said: “An extension to the chilled meats grace period is welcome.

“Nobody wants to see British products being blocked from entering Northern Ireland. This would be totally unnecessary and only add to current tensions.

“However, Boris Johnson must not waste this extension, the Government must stop playing games and instead use this period to come up with a long-term solution to the flaws in the deal he agreed with the EU.”

Angela McGowan, Confederation of British Industry Northern Ireland director, said: “Time must now be spent wisely by the UK and EU to mutually agree workable lasting solutions.

“The people of Northern Ireland need to be put first, starting with a bespoke veterinary agreement and trusted trader arrangements for the movements of goods in the UK internal market.”

Aodhan Connolly, director of the Northern Ireland Retail Consortium, said: “While it is good to see the EU and the UK co-operating on this issue and reaching agreement, this is, in trade terms, a peripheral matter.

“The most pressing issue is the fate of the thousands of food products moving daily from GB to NI, which will be subject to extensive controls when that grace period ends in October.”