Germany's national career Lufthansa will halt flights to and from the Ukrainian cities of Kyiv and Odessa, a spokesperson said on Saturday amid growing fears of a possible Russian invasion.

The company will conduct some last flights to those cities over the weekend before suspending flights from Monday until the end of the month, the spokesman said. It will continue to fly to the city of Lviv in western Ukraine.

Lufthansa is constantly monitoring the situation and will decide on further flights at a later date, the spokesperson said.

Lufthansa follows several other European airlines which have already cancelled services to and from Ukraine.

Germany's foreign ministry earlier told German nationals to leave Ukraine now, as tensions between Russia and Ukraine increased further.

"German nationals are urged to leave the country now," the ministry said in a statement. "A military confrontation is possible at any time." Other countries including Britain and the United States have also asked their nationals to depart.

(With input from agencies)