Nairobi - Britain has advised its citizens to avoid the Kenyan island of Lamu, a popular tourist destination, following a string of attacks and massacres in the coastal region.
A Foreign Office statement said that British nationals should avoid "all but essential travel to Lamu County", which covers the island and part of the mainland - where at least 60 people have been killed in a wave of militant attacks over the past month.
The Kenyan foreign ministry, which has denounced a slew of recent travel warnings as "unfriendly acts", appeared to respond to the latest warning by telling its nationals to steer clear of London's Heathrow airport.
Lamu island is a well-known tourist destination which features ancient architecture and is listed as a unesco World Heritage site, and has in the past hosted wealthy visitors and celebrities such as supermodel Kate Moss, rocker Mick Jagger and US President Barack Obama.
Somalia's al-Qaeda-linked Shabaab have claimed responsibility for the attacks in the Lamu area, saying they were in retaliation for Kenya's military presence in Somalia, where Kenyan troops are part of the African Union force supporting the country's fragile and internationally-backed government.
The Kenyan government, however, has blamed coastal separatists.
The unrest in the coastal region has already badly dented Kenya's tourist industry - a key foreign currency earner and massive employer for the country - at what is traditionally one of its busiest times of the year.
Earlier this year, Britain, France, the United States and Australia also urged their nationals to avoid the port city of Mombasa, which has also been the scene of a wave of shootings and bombings - prompting a British travel firm to evacuate hundreds of package tourists.
Immediately after the release of the latest British travel warning, the Kenyan government warned its citizens against travelling through Heathrow Airport.
"According to information provided by US officials, al-Qaeda operatives in Yemen and Syria were developing sophisticated bombs that could bring down a plane," foreign ministry official Karanja Kibicho said in a statement.
"The information states that Britain would be the most likely country to be affected. Kenyans are advised NOT to travel through London Heathrow where there is substantial threat of a possible attack," it added.