UK Brexit minister David Frost called it a “sensible extension” and a “positive first step” but said a permanent solution for post-Brexit trade to the province was still needed.

“Northern Ireland is an integral part of the UK and its consumers should be able to enjoy products they have bought from Britain for years,” he added.

In Brussels, European Commission vice-president Maros Sefcovic warned that “we are not issuing a blank cheque” and that “this solution is of temporary nature”.

London angered Brussels by threatening to unilaterally extend a grace period for implementing the checks, sparking European threats of reprisals, including targeted tariffs.

But the rhetoric cooled in recent days after the UK government submitted a formal request for an extension.

The UK formally left the European single market and customs union on Jan 1, nearly four years after the public voted to leave the bloc in a landmark referendum.

A last-gasp trade deal was signed on Dec 24, with a separate “protocol” governing trade from Britain — England, Scotland and Wales — to Northern Ireland.

The move, imposing customs controls on certain goods crossing the Irish Sea, was designed to prevent unchecked products from entering the bloc by the back door via Ireland.

But pro-UK unionist communities in Northern Ireland have objected strongly, arguing it puts the province’s place in the wider UK under threat, and has triggered unrest.

An EU official told AFP that the three-month extension would be used to discuss a broader agreement on animal and plant products.

“We do not intend to continue with rolling extensions of grace periods, Northern Ireland deserves stability and predictability, and the best way for that is to have a permanent solution, mutually agreed to… these three months will need to be used wisely.”

Brussels “will be tough” if Britain fails to honour the Brexit deal, the official added.