The Foyle MP claimed yesterday that Sinn Fein is guilty of "old-style majority rule in seeking to circumvent the Good Friday Agreement" and thus ensuring the appointment goes to a unionist.

"When we negotiated the Good Friday Agreement, the SDLP insisted in writing in the D'Hondt system for departmental ministerial appointments in order to ensure that parties could neither vet nor veto a particular minister," said Mr Durkan. "Now, Sinn Fein is conniving with the DUP to bypass the inclusive democracy people voted for in the Agreement.

"They are using their numbers and DUP numbers to deny us the second ministry to which we are very clearly entitled. This is an abuse of power, party-political discrimination and a return to winner-takes-all majority rule."

Mr Durkan said Sinn Fein had made it clear they wanted an Ulster Unionist or Alliance minister.

Sinn Fein Policing spokesman Alex Maskey responded that Mr Durkan had "once again" put securing the justice ministry for his party in front of actually securing the devolution of its powers.

"The recent enthusiasm being displayed by the SDLP to assume a future justice ministry is interesting given the fact that the SDLP never previously argued for such powers to be transferred," said Mr Maskey.

"Indeed in 2001 the then deputy leader Seamus Mallon told us that no further policing legislation was possible. Sinn Fein's negotiating strategy proved him wrong and further important changes were secured in legislation."

A DUP spokesman said he totally rejected Mr Durkan's claims that the unionist party was against the SDLP taking the post. The core issue is that unionist confidence must be adequate before justice powers can be devolved, he said.

"However, one way to build confidence would be for the PIRA's ruling army council to be stood down," he said.

"Mark Durkan would be better served by putting pressure on republicans to achieve this outcome rather than making foolish remarks about conspiracies."