|Police have detained six people for questioning over alleged links to terrorism.
Four of the suspects are held in Mombasa while two have been transferred to Nairobi for further investigations.
Mombasa police commander Patrick Wafula said they raided several homes in the area believed to be sheltering illegal immigrants.
They arrested people of Somali and Tanzanian origin who lacked valid documents. One of the suspects transferred to the city was in possession of a British passport but his visa had expired while another claimed to be Canadian. He said the other suspects lacked documents to permit their stay in Kenya.
Mr Wafula said the suspects had not been taken to court because police had not yet completed their investigation.
Muslim clerics condemned the police raids on residential areas.
Council of Imams and Preachers of Kenya secretary-general Sheikh Mohammed Dor said the officers had no search warrants.
Speaking to reporters at Majengo in Mombasa at the home of Salim Karama whose house was raided by police at 4.30am Sunday, Sheikh Dor termed the search as a violation of human rights.
He said night raids contravened Islamic teachings and asked police to involve imams, chiefs and village elders in night raids.
“We condemn the night raids which were mounted by police at Majengo, Tudor and Barsheba who were looking for terrorist suspects. It was wrong for police to conduct search without warrants or identifying themselves.”
He warned such raids could anger residents at a time when the country seeks peace.