Congo President Joseph Kabila signs the Paris Agreement on climate change at United Nations Headquarters in Manhattan, New York, U.S., April 22, 2016. REUTERS/Carlo Allegri

KINSHASA (Reuters) - Opponents of Democratic Republic of Congo President Joseph Kabila walked out of talks aimed at breaking a dangerous political impasse on Monday, weakening the already tenuous credibility of the negotiations.

Most major opposition parties were already boycotting the talks, which they see as giving a chance for Kabila to justify what they say is his plan to stay in power beyond the end of his mandate in December, breaking constitutional term limits.

But some opposition leaders agreed to the talks on the timing of the presidential election which was due to happen in November but which authorities say cannot be held before July as millions of voters still need to be registered.

“We have suspended our participation ... because the positions were diametrically opposed,” opposition representative Samy Badibanga told Reuters, but he added that the delegation could return if Kabila’s side makes concessions.

The opposition had insisted the presidential election be the next poll held, while the government refused to budge from its position that local elections should take place first, further delaying the presidential vote, Badibanga said.

The government delegation’s spokesman, Leonard She Okitundu, called the walkout “just a negotiating tactic” and was confident the opposition would return.

Congo, Africa’s leading copper producer, has never experienced a peaceful transition of power since independence from Belgium in 1960.

Diplomats and observers fear the political crisis could trigger a repeat of civil wars that killed millions of people between 1996 and 2003.