The United States embassy has issued a fresh warning of an impending attack in Nairobi's hotels and prominent government buildings.
The embassy says the timing of the planned attack is still unknown, but could be in the last stages of planning.
Citing credible intelligence, the warning urged American citizens in Kenya to be vigilant of the personal security.
"The U.S. Embassy informs U.S. citizens residing in or visiting Kenya that the U.S. Embassy in Nairobi has received credible information regarding a possible attack on Nairobi hotels and prominent Kenyan government buildings.
"Timing of the attack is not known, however, the Embassy has reason to believe that the potential attack is in the last stages of planning. The U.S. Embassy urges Americans to remain aware of their surroundings and vigilant of their personal security," a statement from the embassy said.
The warning comes at a time Kenya's security chiefs are pondering on how to tame spontaneous grenade attacks that have rocked the country and which have been attributed to Somalia's islamist group Al-Shabaab.
At least one person was killed and 33 others injured last month when two explosions rocked Mombasa town. (READ: Twin explosions rock Mombasa)
Prime Minister Raila blamed Al-Shabaab for the attacks. (READ: Raila pins blasts on al-Shabaab, as group warns of long war)