Britons leaving Ukraine after Russia sent troops into the east of the country are being given extra support, Foreign Secretary Liz Truss has announced.

Ms Truss urged British nationals to leave the country immediately by “commercial routes”.

She tweeted: “The safety and security of British nationals in Ukraine is our top priority.

“All Brits should leave now via commercial routes while they are still available.

“We are bolstering our teams in the region to support British people as they leave and once they have crossed the border.”

The Prime Minister’s official spokesman said “rapid deployment teams” are being sent to Poland, Moldova, Lithuania and Slovakia to provide consular support to British nationals who leave Ukraine.

Foreign Office travel advice warns: “In the event of a military incursion, it is likely that commercial routes out of Ukraine will be severely disrupted and roads across Ukraine could be closed.”

Wizz Air announced it will continue to operate flights connecting Luton Airport with Kiev and Lviv.

It runs three return flights per week on both routes.

A spokeswoman said: “Wizz Air continues to closely monitor the situation in Ukraine.

We have not made any changes to our schedule

“Currently, we have not made any changes to our schedule and all of our flights to/from Ukraine continue to operate as normal.

“All passengers with booked flights to and from Ukraine are advised to regularly check their mailboxes for further information about booked flights.”

Ryanair and Ukraine International Airlines also operate flights between the UK and Ukraine.

Neither airline has announced any changes to those schedules.

A number of airlines in other countries have suspended flights to and from Ukraine.

They include Air France, Germany’s Lufthansa, Dutch carrier KLM, and Scandinavian company SAS.

Latvian airline airBaltic has halted its overnight flights to and from Ukraine.