Armed police patrolled the streets of Kenya's port city Mombasa Wednesday after a prominent radical Muslim cleric assassinated overnight was buried as martyr.

But Kenya's second city -- a key transport hub for East Africa and a popular tourist destination -- was reported calm in the morning, with the slain cleric's mosque broadcasting appeals for restraint among his supporters.

A hardline Kenyan Muslim cleric was shot dead in the port city of Mombasa on Tuesday, said an Agence France Presse reporter who saw his bloody corpse, as rioting erupted in response.

It was not clear who had killed Abubaker Shariff Ahmed, better known as Makaburi, who was on U.N. sanctions lists accused of being a "leading facilitator and recruiter of young Kenyan Muslims for violent militant activity in Somalia", and for having "strong ties" with senior members of Somalia's Al-Shebab Islamist insurgency.

Kenyan police have arrested more than 650 suspects a day after six people were killed in bomb attacks in the capital Nairobi, the interior minister said Tuesday, in a crackdown on suspected Islamist insurgents.

"This act of cowardice perpetrated against innocent and peace-loving Kenyans who were going about their normal activities is barbaric," Interior Minister Joseph Ole Lenku said in a statement.

A blast in Eastleigh, the main Somali district of the Kenyan capital Nairobi, killed at least five people Monday, an official at the national disaster operations center said.

"Police are securing the area for emergency response services," the official said. Eastleigh has in recent years been the scene of several explosions usually attributed by the police to Islamist extremists.

The International Criminal Court on Monday postponed Kenyan President Uhuru Kenyatta's repeatedly-delayed trial over post-election violence to October, saying it was giving Kenya more time to look for documents wanted by prosecutors.

"Today the Trial Chamber adjourned the case against Uhuru Kenyatta until October 7," the Hague-based ICC said in a statement.

The U.N. refugee agency on Friday criticized Kenya's decision to order all refugees, most of them Somalis, to report to two overcrowded camps after a deadly attack on a church.

"UNHCR understands Kenya's need to address security concerns," said Adrian Edwards, spokesman for the U.N. High Commissioner for Refugees.

Kenya on Tuesday restricted all refugees on its soil to two designated camps in the wake of a weekend attack on a church near Mombasa that claimed six lives.

Kenyans were asked to report any refugees or illegal immigrants outside the overcrowded camps -- Dadaab in the east and Kakuma in the northwest -- to the police.

A group of survivors of sexual violence committed after Kenya's violence-hit 2007 elections took the government to court on Tuesday over its alleged failure to protect them and bring the perpetrators to justice.

The six women and two men, who are supported by a coalition of four human rights organizations, have lodged a complaint in the High Court in Nairobi directed against Kenya's attorney general, director of public prosecutions, and members of the police and public health authorities.

Two people shot when attackers sprayed a Kenyan church with gunfire on Sunday have died of their wounds, taking the total killed in the attack to six, government officials said Monday.

The attack, in the Likoni district near the port city of Mombasa, came amid heightened warnings of a threat of Islamist violence in Kenya and despite boosted security in major cities.

Attackers shot dead four worshipers on Sunday when they burst into a church service near the Kenyan port city of Mombasa, spraying the congregation with bullets, police said.

The attack, which also left about 17 people wounded, came amid heightened warnings of a threat of Islamist violence in Kenya and despite boosted security in major cities including Mombasa.