Malawi has ordered police to shoot "dangerous criminals" who attack albinos in order to sell their body parts for witchcraft.

"Shoot every criminal who is violent when caught red-handed abducting people with albinism," the country's police chief Lexen Kachama told officers at the weekend, according to local media.

As tensions mount in the central African nation of Burundi ahead of presidential elections, journalists and activists say they are paying an increasingly heavy price as standard bearers for free speech.

Civil rights in the small Great Lakes nation, they say, are on the decline -- sacrificed at the altar of President Pierre Nkurunziza's controversial ambition to defy a two-term limit and stay in power for another five years.

With a president who won't go and an opposition determined to blow the final whistle, battle lines are being drawn ahead of elections in the central African nation of Burundi.

Determined to stay put despite a two-term constitutional limit, President Pierre Nkurunziza stands accused of trying to sideline political challengers ahead of the June vote, with measures including arrests, harassment and a clampdown on free speech.

A senior member of Burundi's influential Catholic Church on Saturday called for the release of a radio station boss who has been arrested for complicity in the murder of three Italian nuns.

Bob Rugurika, director of the popular independent African Public Radio (RPA), was arrested in mid-January after broadcasting the purported confession of a man claiming he was one of the killers.

Burundi's ruling party has said it is "ready for compromise" with the opposition to ensure peaceful elections, as warnings mount of the risk of violence in the upcoming key polls.

Opposition politicians however said they were suspicious of the apparent olive branch.

Burundi police on Tuesday arrested the head of a key radio station close to the opposition in connection with the murder of three Italian nuns after broadcasting an alleged confession of the killer.

Bob Rugurika, director of the popular independent Radio Publique Africaine (RPA), was arrested for "complicity" in the murder the three elderly women, killed in twin attacks in the convent in September, his lawyer said.

Burundi police said Friday they had arrested a key opposition leader in connection with a five-day battle earlier this month between the army and gunmen in which some 100 insurgents were killed.

Patrick Nkurunziza, president of the youth wing of the Front for Democracy (Frodebu) party, was arrested on Thursday, police spokesman Pierre Nkurikiye told Agence France Presse.

U.N. Secretary-General Ban Ki-moon told President Joseph Kabila on Wednesday that it was time for decisive action against Hutu rebels in eastern Democratic Republic of Congo.

The phone call to the DR Congo president came as the 20,000-strong U.N. force gears up for an offensive against the rebels whose success hinges on an active role by the Congolese government troops.

Gunmen in Burundi dressed in military fatigues burst into a bar and shot dead three ruling party activists before torching the local party office, police and local officials said Tuesday.

"They tied them up on the ground, then killed them with automatic weapons," said a local official, speaking on condition of anonymity.

U.N. and Democratic Republic of Congo forces seized several rebel bases in an offensive launched Monday against a Burundi rebel group, the National Liberation Forces (FNL), the U.N. said.

A spokesman for the U.N.'s MONUSCO force in DRCongo said troops taking part in joint operations against FNL fighters in the east of the country had taken several Hutu rebel strongholds.