UK troops are to evacuate British citizens from the trouble-hit west African state of Ivory Coast.
The Army's Spearhead Lead Company Group, drawn from the Royal Gurkha Regiment, has already been deployed to neighbouring Ghana.
Defence Secretary Geoff Hoon said the evacuation will also involve a number of RAF transport aircraft.
About 300 members of the UK military will be involved in the operation, which follows anti-foreigner riots.
The news came after it emerged France had begun evacuating its citizens after days of anti-French demonstrations.
Trouble flared after nine French peacekeepers were killed and President Jacques Chirac ordered the destruction of the Ivory Coast's air force.
France has played a lead role in international peacekeeping in Ivory Coast - a former colony - after President Laurent Gbagbo broke an 18-month ceasefire with rebels bombing their positions and killing the nine French soldiers.
The decision to destroy the African nation's small air force prompted riots against French and other foreign nationals.
In a Commons written statement, Mr Hoon said: "We are always prepared to deploy British forces to evacuate UK nationals should their lives be placed in jeopardy," he said.
"In light of the deteriorating security situation in Ivory Coast, a military reconnaissance team was deployed earlier this week to assess the requirement to evacuate UK nationals.
"Following this reconnaissance, the Foreign and Commonwealth Office has requested British forces to undertake an evacuation of UK nationals and others over the next few days."
Mr Hoon added that about 400 people in Ivory Coast were entitled to the protection of the British armed forces.
"We would expect the operation to last days, not weeks," he added.
The Gurkhas flew into Accra, Ghana's capital, on Wednesday and are on "immediate notice" to move into Ivory Coast to help British people to get out of the country should it become necessary.