Britons are being advised stay away from Kenyan coastal areas within 93 miles of the Somali border after a second armed gang attack in a month.
The Foreign Office issued its warning last night after a French woman was kidnapped earlier yesterday from a beach resort in the Lamu archipelago, northern Kenya, by ten heavily armed Somali militants.
On September 11, Britons David Tebbutt, 58, was killed and his wife Judith, 56, abducted by armed gunmen from a resort near the popular tourist town of Lamu.
Security forces yesterday tracked down and surrounded the pirate boat believed to be carrying the French hostage, identified as Marie Dedieu by the Kenyan government.
In a statement, the FCO said: "We advise against all but essential travel to coastal areas within 150km of the Somali border, following two attacks by armed gangs in small boats against beach resorts in the Lamu area on 11 September and 1 October 2011.
"This advice will be kept under review. Both attacks were on beach-front properties, with two Westerners kidnapped and one murdered.
"Beach-front accommodation in that area and boats off the coast are vulnerable."
The Tebbutts, from Bishop's Stortford, were the only guests at the Kiwayu Safari Village, 25 miles from the Kenya-Somalia border.
The FCO said its travel advice is "under constant review in the light of the situation on the ground".
"Travel advice is based on objective assessments of the risk to British nationals, whose safety is our main concern," said the statement.
Full travel advice for Kenya can be found on the Foreign Office website.
Foreign Secretary William Hague told Sky News's Murnaghan programme: "Clearly, we are worried about the situation there. There is the case of Mrs Tebbutt that we are trying to deal with as best we can.
"But now we are seeing possibly copycat kidnappings taking place. That is very alarming.
"That's why we have said within 150km of the Somali border, people have to be very conscious of that.
"It is sad, and we are working with the Kenyan authorities and urging them to improve security in any way they can."