A local Kenyan official has been killed in what police say is a retaliatory attack for the arrest of a secessionist leader in Coast province.
Salim Changu was hacked to death in the coastal town of Kwale, police say.
He was attacked shortly after Mombasa Republican Council (MRC) Omar Mwamnuadzi was arrested during a gunfight at his home, in which two people were killed.
Tension has been rising in Kenya ahead of general elections due in March 2013.
More than 100 people have been killed in ethnic clashes in the south-east Tana River area since August, in the bloodiest violence since the disputed 2007 presidential election.
Regional police chief Aggrey Adoli told the BBC that Mr Changu, the assistant chief for the Kombani area, was killed by MRC supporters after going to Mr Mwamnuadzi's house to see what had happened overnight.
"It was a revenge attack," he said.
Earlier, police launched an operation against the MRC following accusations that it planned to disrupt school examinations.
Two of Mr Mwamnuadzi's bodyguards were killed during the raid on his home in Kwale and 38 people were arrested, the Daily Nation newspaper reported.
Thirteen people have since been charged - some with possession of offensive weapons, others over T-shirts with pro-independence slogans.
They denied the charges but were remanded in custody.
In July, Kenya's High Court lifted a ban on the MRC, which the government had outlawed in 2010 after accusing it of being a criminal gang.
However, Mr Adoli told the BBC's Focus on Africa programme that despite the court ruling the group was "still illegal".
The MRC accuses successive governments of marginalising the ethnic groups living along the coast, which is the centre of the country's tourism sector, and giving land to outsiders.
Calls for the secession of the mainly Muslim coastal region tend to intensify in the run-up to general elections, analysts say.