Japan plans to withdraw some of its embassy staff from Ukraine amid the Eastern European country's heightened tensions with Russia, a senior Foreign Ministry official has said.

The embassy has about 20 staff members and the ministry will keep only those needed to help Japanese nationals living in Ukraine, the official said Friday. Family members of the embassy staff have already begun to leave.

"In a crisis situation, it's not necessary to keep all staff members there," the Japanese official said.

Rising concerns that Russia may invade Ukraine have led to increased diplomatic efforts by the United States among others to diffuse the tension. The United States and Britain have already decided to evacuate family members of their embassy staff in Ukraine.

The Japanese ministry has warned against traveling to Ukraine for any purpose, raising its advisory to the second-highest Level 3. It has been urging the roughly 250 Japanese nationals residing in the country to leave.

Prime Minister Fumio Kishida has told parliament that Japan is watching Russia's military build-up near Ukraine's border and related developments with "grave concern," saying that it will deal with the issue appropriately using the framework of the Group of Seven industrialized nations.