Opposition parties in Democratic Republic of Congo said on Friday they would stage rallies to put pressure on President Joseph Kabila to step down when his mandate expires at the end of the year.

The announcement comes a year after at least 40 people were killed when security forces opened fire on demonstrators and analysts say a repeat of the violence is possible.

He is yet to outline his plans, but allies have recently suggested delaying the vote by up to four years to clean up voter rolls.

A coalition of opposition parties said in a statement the protests would include one to commemorate the deaths a year ago. The protests then were against a proposed revision of the electoral code that critics called a ploy to delay elections.

"We thus launch a vibrant patriotic appeal to the Congolese people ... to internalize the fact that a group of individuals wants to exercise power in violation of the constitution," it said.

The statement echoes calls by Congo's powerful Catholic church for a march on Feb. 16 to demand respect for the constitution.

Congo's largest opposition party, the Union for Democracy and Social Progress (UDPS), did not sign. It says it hopes to participate in a national dialogue announced by Kabila last November to resolve logistical obstacles to holding the presidential and other elections.

Most other opposition parties have vowed to boycott the dialogue, which they say is aimed at postponing elections.

Since independence in 1960, there has not been a peaceful political transition in Congo, which saw decades of autocratic rule followed since 1996 by a series of wars and rebellions, mainly in the east.