By Caroline Gluck BBC Seoul correspondent

Eleven MPs have split from South Korea's governing Millennium Democratic Party, saying they had no confidence that the party's candidate could win presidential elections.

The group says it will form a negotiating bloc to push for a single reformist candidate to stand against the opposition conservative candidate.

News of the latest defections was not unexpected.

In the last few months there has been mounting unrest within the MDP, with many believing that their candidate, Roh Moo-hyun, was unlikely to win in end-of-year elections.

The image of the party, which was founded by President Kim Dae-jung, has been badly dented by a series of corruption scandals involving senior government officials and two of the president's sons.

New party

Growing numbers of party lawmakers are now calling for an alliance with another presidential candidate, independent lawmaker millionaire businessman Chung Mong-joon.

His party, National Unity 21, will be officially launched on Tuesday.

The lawmakers say the two sides should field a single candidate standing on a reformist platform. They believe it is the only way to defeat Lee Hoi-chang, candidate of the opposition conservative Grand National Party, who is currently leading in opinion polls.

Mr Roh has now said he is willing to do so but only if that happens through a national open primary.

The ball is now in Mr Chong's court but failure to reach agreement could result in the collapse of the MDP and increase the likelihood that a conservative president, taking a tougher line towards North Korea, will be elected in December.