Royal Marines could be deployed to guard the British Embassy in Ukraine, it has been reported, amid concerns UK diplomats could be targets for Russian special forces.
It is believed up to 30 British commandos are stationed inside the building in Kyiv, according to the Mirror.
The Ministry of Defence (MOD) has stated that they would not be engaged in combat, however.
An MOD spokesperson said: "British military personnel have been deployed to Ukraine to support the UK's diplomatic presence in the country, and to support discussions around the significant training being offered to the Armed Forces of Ukraine by the UK.
"They serve no combat function.
"We take the safety and security of our personnel seriously and this deployment is kept under constant review," they added.
It comes as the chair of the Defence Committee said British forces would run out of ammunition in "two weeks" if they were at war with Russia.
Talking to Forces News, MP Tobias Ellwood said that the UK has gifted so much equipment to Ukraine that it would have a "shortfall" of its own if it was to tackle Russia itself.
"The amount of ammunition that Ukraine is expending, if we went to war, we'd run out in two weeks," Mr Ellwood said.