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 flight 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.
“the airline continues to monitor the situation closely and is in close contact with national and international authorities,” it said.
Mr Johnson said 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.
Late last month, several European airlines said they would alter their schedules to limit time spent in Ukrainian airspace.
Washington and its allies are warning that Russia; which has 100,000 soldiers massed on the border with Ukraine; could invade at any moment. Russia has denied that and opposes NATO bases near its borders.
In recent weeks, more than a dozen countries have urged their citizens to leave Ukraine.
Many airlines have generally avoided flying over eastern Ukraine since 2014; after Malaysia Airlines flight MH17, flying from Amsterdam to Kuala Lumpur; was shot down over separatist-held territory on July 17.
All 298 people on board, 198 of whom were Dutch citizens, were killed.
A Dutch Safety Board investigation revealed that the Boeing 777 was hit by a Russian-made surface-to-air missile.
Ukraine and Dutch prosecutors accused Russia-backed armed groups operating in the area of launching the missile.
President Vladimir Putin rejected allegations that Russia was behind it.