The prospects of the formation of a fully functioning Stormont Executive were complicated yesterday by a DUP warning that it may not share power with the Ulster Unionists.
Northern Ireland's 108 Assembly members yesterday attended the first sitting of the body at Stormont since it was suspended in October 2002.
The proceedings began without any sense of rancour and with members observing a minute's silence in memory of murdered Ballymena teenager Michael McIlveen.
However Progressive Unionist Party leader David Ervine's decision to sign the register as a member of the Ulster Unionist Assembly group provoked DUP anger and a fresh warning about power-sharing with any party connected to paramilitary groups. Mr Ervine's move is aimed at securing an extra ministerial position for the UUP under the d'Hondt procedure, which is used to share out Executive seats among the main parties based on their relative strength in the chamber.
Before the close of proceedings the DUP leadership pressed newly-appointed Presiding Officer Eileen Bell to review the development.
Her decision on the status of one party leader signing up for another party's Assembly group, following legal advice, is due later today, but more time may be necessary before the legal position becomes clear.
A clearly angry Dr Paisley, speaking after Assembly adjourned, warned his party would not enter government with anyone connected to paramilitary activity.
The DUP is denouncing Mr Ervine's decision to register with the Ulster Unionist Assembly group while retaining the leadership of the PUP which is aligned with the UVF which is not on ceasefire. Under the d'Hondt procedure, the Executive's 10 ministerial positions are shared among the main parties relative to their overall strength in the Assembly.
With 24 seats, Ulster Unionists could have expected two ministers. With Mr Ervine bringing their total to 25 they could claim the 10th ministerial position ahead of Sinn Féin which has 24 members, giving three seats.
Speaking outside the chamber afterwards SDLP leader Mark Durkan, accused the Ulster Unionists of hypocrisy.
Branding the move as "a stroke too far", he added: "Never again can the UUP use allegations of IRA paramilitary activity as an excuse not to go into government without being asked to answer for the UVF."
Sinn Féin said the need for agreement on the formation of an Executive took precedence over the Ervine registration row and declined to comment further.
Assembly members are due to vote on the appointment of First and Deputy First Ministers next Monday and Gerry Adams is expected to nominate Ian Paisley. This is certain to fail, thus postponing the running of the d'Hondt procedure.
Yesterday's session began with opening remarks by Mrs Bell who stated: "This Assembly has been established to make preparations for the restoration of devolved government in Northern Ireland, and a fully restores Assembly."
She also read a letter from Northern Secretary Peter Hain in which he stated his hope for "a rapid transition of the Assembly to full devolution".
Mrs Bell asked members to stand for a minute's silence in memory of murdered Ballymena teenager Michael McIlveen before calling each of them to register as "unionist", "nationalist" or "other".
Sinn Féin members will be there this morning but have made it clear they have no interest in debating the formation of a working party on economic matters which has no power. The public session will therefore see the chamber three-quarters full at best.