Three NATO warships arrived in the southwestern Finnish port of of Turku on Monday to train with Finland's navy as Helsinki considers the possibility of joining the U.S.-led alliance amid increased tensions with Russia over Ukraine.

Latvian minelayer LVNS Virsaitis and minehunters Estonian ENS Sakala and Dutch HNLMS Schiedam will train with two minehunters from Finland's coastal fleet, the Finnish defence forces said in a statement.

The two-day exercise, set to commence on April 28, will prepare the Finnish ships to take part in NATO response forces in 2022 and focus on "mine countermeasures and working in a multinational framework", the statement said.

Finnish Prime Minister Sanna Marin said on April 13 that her country would take a decision in the next few weeks about whether to apply to join NATO, prompting an angry response from Russia.

Finland and neighbouring Sweden are close partners with NATO but have shied away from joining the 30-member alliance, founded in 1949 to counter the Soviet Union during the Cold War.

Marin said the option to join NATO had to be carefully analysed but that everything had changed since Russian forces invaded Ukraine on Feb. 24. Finland shares a 1,300-km (810-mile) land border with Russia.

(Reporting by Essi Lehto Editing by Gareth Jones/Mark Heinrich)