British nationals in crimea "should leave now"
Crimea - taken in 2006 Photo: Argenberg
The FCO's caution arrives as unrest and violence has grown across Ukraine and Russia has taken control of the Crimea region.
The FCO has now updated its travel advice for the country, recommending against "all travel" to Crimea.
The Foreign Office has urged all UK citizens in Crimea to leave amid escalating violence.
"The FCO is not able to provide consular services to anyone choosing to remain in Crimea," it warned. "Events in Ukraine are fast moving. You should monitor this travel advice regularly."
The situation in Kyiv and other cities has "calmed considerably", the FCO wrote this week, but advises against travel to the peninsula in the south of the country.
"Flights have now resumed as of 2 March but we do not advise British nationals to leave via this route until the situation becomes more stable," added the FCO. "Train and bus routes out of the peninsula are still operating. There are reports of road blocks, but traffic is able to get through. If you’re currently visiting or living in Crimea, you should leave now."
Around 80,000 British nationals visited Ukraine in 2012, but there is no confirmed number of Britons in the country at the moment. The FCO told the BBC that "a very small number of people" are affected.
For those choosing to remain, the Foreign Office cautions them to "keep a low profile".
Negotiations continue between the countries. For up to date travel advice, visit https://www.gov.uk/foreign-travel-advice/ukraine.