Kenyan police

A Kenyan official says police officers have arrested two Iranians suspected of being involved in terrorism, reports The Associated Press.

Aggrey Adoli, the police chief in charge of Kenya's coastal region, said Friday the two were arrested in Nairobi this week and that one led counter-terrorism officers to the coastal town of Mombasa to recover 15 kilograms (33 pounds) of a powdery substance that police believe is explosive material.

The U.S. Embassy in Kenya on Friday warned of an imminent threat of a terrorist attack in Mombasa and said all U.S. government personnel must leave the city. It also said travel to Mombasa by U.S. officials has been suspended until next month.

Kenya has been facing the threat of an attack from al-Qaida-linked Somali militants. The al-Shabab insurgents have vowed to bomb an area of Kenya for sending its troops into Somalia.