More than 100 police officers are reported missing in two towns in the war-torn Democratic Republic of Congo, says the United Nations.

Four policemen in the second city of Kisangani were confirmed dead and an inquiry has been opened to ascertain what had happened to the others, the head of the UN in DR Congo, Amos Namanga Ngongi, said on Tuesday .

At least 50 of the officers were to start training with the United Nations on Wednesday to take over security after the planned demilitarisation of Kisangani.

They disappeared during last week's mutiny by soldiers of the rebel Rally for Congolese Democracy.

Local sources told the BBC that the policemen had been killed by the Rwandan-backed RCD.

Fear

But Mr Namanga Ngongi said that since the disappearance of these policemen, another 85 police officers had deserted the south-eastern town of Pweto, which was recently demilitarised.

The policemen might have deserted for fear of suffering the same fate as their colleagues in Kisangani, aid agencies say.

DR Congo has been at war for more than three years

The Catholic Church says 50 people were killed in the violence and in the reprisals which followed.

On Tuesday, the situation in Kisangani was still tense, according to Mr Namanga Ngongi.

He said that security forces were still arresting people in connection with last week's mutiny.

The BBC's Mark Dummett in Kinshasa says that many human rights activists in Kisangani are now in hiding, fearing they may be next in line.

Demilitarise

Mr Ngongi described the events in Kisangani as "murderous madness" and noted "the disproportionate number of victims".

He asked how many more civilians needed to die in Kisangani before people realised that violence was not going to solve the DR Congo's problems.

He urged the RCD to do everything possible to protect the population of Kisangani and to demilitarise the city.

The UN Security Council has called for the demilitarisation of Kisangani as part of the Congolese peace process.