7 January 2012The Foreign Office has said terrorists could be in the final stages of planning an attack in Kenya, and has urged British nationals there to be cautious. Visitors to Nairobi are being warned to avoid places such as hotels, shopping centres and beaches. British counter-terrorism officials have been helping Kenyan police, who found explosives and bomb-making equipment in a raid in Mombasa last month. A British citizen was among those arrrested in that raid. The Kenyan authorities are looking for a British woman thought to have links to the al-Qaeda-linked group, al-Shabab. The BBC's security correspondent, Frank Gardner, reports that it is a "very tense" time.