According to the 1998 peace agreement, the regional government in Belfast must be led jointly by Catholic nationalists and Protestant unionists. The British Minister for Northern Ireland, Chris Heaton-Harris, had recently held talks with the political parties in order to persuade them to form a government.

If no agreement is reached by Friday, London must by law call new elections for the regional parliament.

In the regional elections in May, the Irish nationalist party Sinn Fein won a majority for the first time in Northern Ireland's history. However, the DUP is boycotting Parliament because it rejects the post-Brexit customs regime for Northern Ireland. The Unionists fear that this will lead to increasing secession from the rest of the United Kingdom.

Thanks to the Northern Ireland Protocol, the province will remain part of the European single market even after Brexit, but there are goods controls between Great Britain and Northern Ireland.

The British government originally approved the regulation to prevent controls between the EU country Ireland and Northern Ireland, as this could endanger the peace process in the former troubled region. Since then, however, London has been pushing Brussels to roll back the protocol and has enacted its own legislation to circumvent it.

DUP chief Donaldson said on Wednesday he had tried to persuade Heaton-Harris of the need to "clean up the debris of the protocol". An election would do little to change the stalemate.

Sinn Fein CEO Michelle O'Neill called on the DUP to stop "blocking" the formation of an executive and to "work with the rest of us."

The political impasse in Northern Ireland was also part of a phone call between Irish Prime Minister Michael Martin and Britain's new Prime Minister Rishi Sunak on Wednesday. Regarding the Northern Ireland protocol, Sunak stressed that he hoped for "a negotiated solution" and that "all parties meet the current challenges with pragmatism and good will," said Downing Street.