LONDON - British lawmakers will next week debate the central element of the government's recent deal with the European Union to reform post-Brexit trade rules for Northern Ireland.

The government said there would be a debate in the House of Commons on March 22 on a motion to approve the measures needed to implement the so-called "Stormont brake".

The brake enables Britain to stop new EU laws from applying to goods in Northern Ireland if requested by a third of lawmakers in the province's devolved legislature.

The deal, announced last month, seeks to resolve tensions caused by the Northern Ireland protocol - a complex agreement which set the trading rules for the British-ruled region that London agreed before it left the EU but now says are unworkable.

The head of Northern Ireland's Democratic Unionist Party (DUP) this week voiced his strongest concerns to date over the UK-EU deal, saying his party was seeking changes from the British government.

A key test of the deal is its ability to convince the DUP to end a year-long boycott of Northern Ireland's power-sharing government over the original post-Brexit trade rules.

The debate next week is expected to be followed by a vote on measures to implement the brake. The opposition Labour Party has said it supports the deal overall, so those measures are likely to pass comfortably.

However, the debate will provide the first tangible test of sentiment among the DUP and also within Sunak's own Conseravtive Party.

(Reporting by Andrew MacAskill; editing by William James)