Lufthansa, the German airline, said it will suspend flights to the Ukraine capital Kyiv from Monday amid growing fears of a Russian invasion.
The airline said it will also stop flights to Odessa, a key port on the Black Sea.
“The safety of our passengers and crew members is our top priority at all times,” said Lufthansa.
Prime Minister Boris Johnson warned on Sunday that Russia is planning “the biggest war in Europe since 1945”.
Last week, the Dutch airline KLM said that it was suspending flights to Kyiv. Lufthansa said it will operate flights on Sunday before the suspensions come into force on Monday. They are expected to remain in place until the end of February.
On Saturday, Germany’s Foreign Office urged its citizens to leave Ukraine “now”. It said: “If there is a Russian attack on Ukraine, the options for assisting German nationals are very limited.”
Lufthansa said it continued “to monitor the situation closely and is in close contact with national and international authorities”.
It added: “Affected guests will be informed and rebooked on alternative flight connections.”
The airline usually operates 74 flights to Ukraine every week under its Lufthansa banner or the other carriers it owns which include Austrian Airlines, Eurowings and Swiss.
Lufthansa said it would continue to fly to Lviv in Western Ukraine.
Mr Johnson told the BBC that evidence suggests that Russia intends to launch an invasion that will encircle Kyiv.
“All the signs are that the plan has already in some senses begun,” he said.
Ryanair and Wizz Air also operate flights to Ukraine and last week said they would continue to fly to the country. Ryanair is the largest airline which flies between Europe and Ukraine, followed by Wizz Air.
‘Don’t panic’
Ryanair’s chief executive Michael O’Leary said last week: “It is important not to panic.
“Is it our duty and obligation to support the people of Ukraine as long as there is no war or missiles flying there.”
The UK’s Foreign Office has advisedthat British nationals “should leave while commercial options remain”.
“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,” it said.