Cameroon's Interior Minister Paul Atanga Nji says opposition leader Issa Tchiroma Bakary will face legal action over allegations he incited "violent post-election demonstrations". 

At least four protesters have been killed during clashes between security forces and opposition supporters since Cameroon's election on 12 October, with 92-year-old President Paul Biya winning an eighth consecutive term.

Tchiroma Bakary insists he won the election, a claim dismissed by Biya's ruling party, the Cameroon People's Democratic Movement (CPDM).

Violent crackdowns by police and security officers on protesters have alarmed the international community, with the UN, African Union and EU calling for restraint.

On Tuesday, Nji accused Tchiroma Bakary of organising what he said were "illegal" protests leading to the loss of lives, and also criticised him for declaring victory in the election.

He added that Tchiroma Bakary's "accomplices responsible for an insurrectionary plan" will also face legal action.

Paul Biya, who came to power in 1982 and is now the world's oldest head of state, won the 12 October election with 53.7% of the vote, compared to 35.2% for Tchiroma Bakary, according to Cameroon's Constitutional Council.

Tchiroma Bakary is yet to respond to the government's decision to try him, but he had previously told the BBC that he would not accept a stolen vote - and that he was not afraid of being arrested.

On election result day, he said armed men opened fire on protesters assembled near his residence in Garoua, fatally wounding at least two civilians.

On Tuesday, the interior minister revealed that an investigation would be launched into violent incidents before and after the announcement of the election results.

"During these attacks, some of the criminals lost their lives," he said, without providing a specific number of protesters who have been killed in the clashes.

Nji added that several members of the security forces had also sustained serious injuries.

Although Nji insisted the situation nationwide was now under control, protesters remain active in some parts of the country, especially in Douala and Garoua, where demonstrators mounted roadblocks on Tuesday, and burnt tyres on the streets.

Analysts warn the post-electoral violence could plunge the country into a political crisis.