Police on Monday arrested a man and held him for hours on suspicion that he was one of the world's most wanted fugitives.

The officers from the Anti-Terrorism Police Unit pounced on the man as he walked on Kenyatta Avenue in Nairobi after someone allegedly called saying he resembled terror suspect Fazul Abdulla.

The man had been walking near the Serena Hotel at around midday when plainclothes officers approached him and whisked him away.

Officers close to the "operation", however, later said that the man they arrested was not Fazul but a look-alike.

But even by Monday evening, the man was still being interrogated just to be sure that the officers are not cheated out of what could be one of the world's most important arrests.

Another escape

"He is still being held, but may be released after we are sure that he is not the man we are looking for," a source in the unit said.

The officers have been unrelenting, with dotted stories of close shave escapes by the man believed to have masterminded some of the world's most destructive terrorist attacks.

Eight days ago, four members of one family were arrested at their home over links with Fazul.

But the manner in which the officers conducted the raid point to a possibility that they believed Fazul himself may have been in the house.

A week earlier, another escape from a police dragnet had been reported, the second in as many weeks.