Policemen inspect the secured section at the scene of the blast in Eastleigh suburb of Kenya's capital Nairobi December 7, 2012. A bomb blast in a predominantly Somali district of the Kenyan capital of Nairobi on Friday killed five people and wounded at least eight, the Kenyan Red Cross said. REUTERS/Stringer

Nairobi -

A grenade attack near a Nairobi mosque has killed five people and heightened security concerns three months before Kenya goes to the polls.

“Two more people have died in hospital, the death toll is now five,” Nairobi Police Chief Moses Nyakwama told AFP, updating an earlier toll of three.

A grenade was hurled at worshippers leaving a popular mosque minutes after the end of evening prayers on Friday, according to police and witnesses.

“We have sent more officers on the ground to ensure there is peace,” Nyakwama said.

Police had to break up groups of protestors who had spontaneously taken to the streets on Friday evening to vent their anger.

The incident was the latest in a string of attacks to rock Nairobi's Eastleigh neighbourhood, which is home to a large Somali ethnic population.

It follows a roadside bomb explosion also in Eastleigh district on Wednesday evening, that killed one person and wounded eight others, as well as a bomb on a bus last month that killed nine.

Kenya has suffered a string of attacks often blamed on Al-Qaeda-linked Shebab militants since it invaded Somalia last year.

Kenyan troops, now integrated into an African Union force, seized the Shebab bastion of Kismayo in September, a key southern Somali port, prompting warnings of retaliation from both the insurgents and their Kenyan supporters.

The Shebab have denied involvement in previous similar bombings. - Sapa-AFP