The SDLP reserves the right to go into “constructive opposition”, leader Dr Alasdair McDonnell has told his party’s annual conference in Belfast.

Moreover, ahead of next May's British general election Dr McDonnell again ruled out any prospect of agreeing an electoral pact with Sinn Féin. He said the SDLP will stand candidates in each of the North's 18 constituencies while he as MP for South Belfast and fellow MPs Margaret Ritchie in South Down and Mark Durkan in Foyle were already campaigning to be returned to the House of Commons.

Dr McDonnell said the party would not be "distracted" by talk of pacts , from either Sinn Féin or the Ulster Unionist Party. He also said that the SDLP still had at "its heart the vision of a new and united Ireland" which "accommodates all cultures, traditions, religions and beliefs".

"We are not in the business of sectarianism, petty nationalism or militarism," he told some 300 delegates attending the party's 43rd annual conference in the Ramada Hotel in south Belfast. "The SDLP are solely in the business of persuasion and common decency. There can be no other pathway to the way ahead in Northern Ireland. "

Also speaking at a side meeting at the conference was Maíria Cahill. In his speech Dr McDonnell made no direct reference to Ms Cahill but said "republicanism which should have been a term of inclusion . . . has been sullied by those who would force their will on others, making it the mirror image of that under which we suffered so long."

He added: “The SDLP wants to build a new Ireland where understanding, equality, reconciliation and inclusion are principles we pass on confidently to our children and where the tyrannies of sectarianism, hatred and conflict are repulsive memories of what we have irrevocably consigned to the past.”

Dr McDonnell signalled that the SDLP which has one department in the Northern Executive – environment run by Derry MLA Mark H Durkan – may at some stage abandon that ministry to go into opposition.

He said that in the current talks aimed at ending the logjam threatening the very future of the Northern Executive and Assembly that the SDLP will argue for a properly structured formal opposition at Stormont. “In the meantime if other parties don’t get to grips with their responsibilities and we can’t settle on an agreed way forward then we will reserve the right to operate from a position of constructive opposition. The present structures do not stop us from opposing bad legislation or from highlighting the flaws and the problems with the two bigger parties. Nor do they stop us from saying ‘no’,” he said.

“We will not be part of a broken and politically bankrupt Executive if it doesn’t get its act together . . . Opposition has to have clearer definition and serve the public interest. It is however an option we will reserve, we will review and we will evaluate on an ongoing basis.”

Dr McDonnell told delegates that the expectations for the talks were very low despite the hopes of the people of Northern Ireland.

"People want the Assembly to work, they want Stormont to work, they want government Ministers to work together. People want the Assembly to deliver, they want change for the better, change they can rely on," he said. "But it isn't happening. As things stand Sinn Fein and the DUP do not, cannot and will not work constructively together. We don't have partnership government – we have a self-serving partisan gridlock."