* Kenya trying to break up militant networks
* Death of Islamist could stir unrest on coast
* Police deny extra-judicial killings (Adds analyst comment, background on church attack last month)
By Joseph Akwiri
MOMBASA, Kenya, April 1 (Reuters) - A prominent Kenyan Islamist, accused by the United States and U.N. Security Council of supporting the Somali militant group al Shabaab, was killed on Tuesday, a police officer at the scene and a witness said.
An officer pointed to a dead body a few km (miles) from the port city of Mombasa and said it was that of Abubakar Shariff, also known as Makaburi.
"Our brother Abubakar Shariff Makaburi has left us. He is dead," a preacher at a mosque in Kisauni, a Muslim-dominated area near Mombasa, said through a loudspeaker. "May his soul rest in peace. He has died a brave death."
There was no immediate official police comment.
A Reuters witness at the site identified the corpse, which appeared to have bullet wounds to the body and head, while dozens of Makaburi's supporters gathered nearby demanding police hand over the body.
Makaburi's death could stir fresh unrest in the coastal area where most of Kenya's Muslims live. Muslim youths clashed with police for three days in February after a man was killed during a police raid on a mosque used by firebrand preachers.
Kenyan police have dismissed Islamist charges that they are to blame for a series of extra-judicial killings.
The east African country, the region's largest economy, is still reeling from an al Shabaab attack on a shopping mall in Nairobi in September in which at least 67 people were killed.
Kenya is trying to break up militant recruitment networks among its Muslim community in an effort to end attacks by Somali Islamist militants and sympathisers bent on punishing it for sending troops to Somalia to fight al Shabaab rebels.
Tensions on the coast have increased since an attack last month by gunmen on a church in the Mombasa area in which six worshippers were killed. There was no claim of responsibility, but it was similar to other such assaults blamed on Islamists.
"I KNOW I WILL BE KILLED"
A report by the U.N. monitoring group on Somalia said Makaburi had an influential role in the Kenyan-based Islamist militant group al Hijra, suggesting he had called for attacks on a range of targets in Kenya.
The group said al Hijra working on behalf of al Shabaab.
"He became the central figure in terms of al Hijra, in terms of the operations, in terms of relations with al Shabaab," one Western diplomat said.
He said Makaburi had become the most high-profile Islamist activist in Kenya after the killing of Islamist cleric Aboud Rogo in August 2012.
"I know I will be killed," Makakuri had told Reuters in October, saying the police would seek ways to justify shooting him. "I'm ready to die for it. If they want to or if they don't, they will give me martyrdom."
The U.N. Security Council and the United States had accused Makaburi of raising funds and recruiting for al Shabaab.
At least one other body was also at the scene on Tuesday, alongside that of Makaburi's, a Reuters witness reported.
"Where are you taking those bodies? Give us our bodies. You are not taking them anywhere," shouted one youth among the crowd as police loaded the corpses into a police truck.
Police fired in the air to disperse supporters. (Additional reporting by Drazen Jorgic in Nairobi; Writing by Edmund Blair; Editing by Andrew Roche)