Police detained 52 people in Kenya's main port city, a day after an officer was killed in a suspected Islamist revenge attack, heightening tensions in an area where the authorities say militant Islamist is spreading.
After a recent spate of attacks, police detained dozens of youths from mosques in Mombasa which they say are used by radical preachers as recruitment centres. The arrests have angered many Muslims in the mainly Christian nation.
A senior officer with Kenya's counter-terrorism police unit was shot dead by gunmen on Thursday in Mombasa, in what police said could be revenge for the crackdown, prompting a new round of arrests that diplomats say will likely fuel more violence.
Geoffrey Mayek, Mombasa county police chief, told Reuters that police had made the 52 arrests to try to track down the killers, who are believed to have taken the rifle of the slain police officer -- Ibrahim Mohammed.
"We must get the killers and also recover the stolen gun," he said. "This operation will go on until we achieve that. In the meantime we are gathering crucial information from those we arrested. Those we find innocent among them will be released."
Somali Islamist group Al Shabaab has claimed most of the recent attacks along the coast and elsewhere, saying it is punishing Kenya for sending troops to Somalia as part of an African Union force battling the rebels.
Diplomats acknowledge that Kenya faces a difficult task in dealing with radical youths but say the regular round-ups in which dozens are often detained at a time, with almost all released without charge, is playing into the hands of militants.
Local residents accused police of using excessive force during Friday's crackdown.
"They have beaten up our children and husbands and arrested many who are innocent. It seems this police brutality will never end," said Salma Binti Ramadhan, whose husband was detained.
She said two of her sons and other youths in the area had left for fear of the impending crackdown.