The move by Northern Ireland's second biggest party follows Sinn Fein vice-president Pat Doherty's dismissal of arms decommissioning as a "dead end issue".

BBC Ireland correspondent Mark Devenport: old party alliances will break down (2'30")

In the wake of the 71% backing in Northern Ireland for the Good Friday peace deal, his party said it wanted a pact with the SDLP.

The aim would be to strengthen the nationalist vote for the Northern Ireland Assembly.

But there are unlikely to be any agreed nominations when the sides name their candidates for the June 25 poll.

SDLP senior negotiator Brid Rodgers said: "A pact would be totally contrary to the spirit of the times because we are now going to begin to work together across the (community) divide and I think nothing could be gained from such an arrangement.

"The idea doesn't merit serious consideration because we have begun a new dispensation.

"It is important the 71% people who voted for that change will have it delivered. That change can best be delivered by people voting right down the election ballot paper for all the pro-agreement parties."