The government is banning travel to Ukraine amid rising military tensions between the former Soviet state and Russia.

The foreign ministry will issue a Level 4 travel alert, the highest in its four-tier system, effective from Sunday, banning travel to all regions in Ukraine.

The ministry said it's a preventative measure and urged Korean nationals remaining in the country to evacuate immediately to Korea or another country.

It also asked citizens with travel plans to Ukraine to cancel them. 

Under a travel ban, people failing to evacuate can be punished by law and those who wish to visit the region must seek permission.

Currently, some 340 South Koreans remain in Ukraine, including embassy staff, missionaries and students.

The government in late January raised the travel alert to Level 3 for 12 provinces in southern, eastern and northern Ukraine, advising evacuation. 

The defense ministry is also ready to mobilize assets to transport South Korean citizens as a contingency.

This comes amid fears that Russia could invade Ukraine with troops deployed along the border.