Finland will decide to apply for NATO membership on May 12, Finnish newspaper Iltalehti reported late on Sunday, citing anonymous government sources.
The decision to join will come in two steps on that day, with Finnish President Sauli Niinisto first announcing his approval for the Nordic neighbour of Russia to join the Western defence alliance, followed by parliamentary groups giving their approval for the application, the paper reported.
Russia's invasion of Ukraine has pushed Finland and Sweden to the verge of applying for NATO membership and abandoning a belief held for decades that peace was best kept by not publicly choosing sides.
Reuters was not immediately able to verify the details provided by Iltalehti.
Under the Finnish constitution, the president leads Finland's foreign and security policy in cooperation with the government.
The decision will be confirmed in a meeting between the President and the government's key ministers after the President's and the Parliament's initial announcements, the paper reported.
Russia, with which Finland shares a 1,300-km (810-mile) border and a pre-1945 history of conflict, has warned it will deploy nuclear weapons and hypersonic missiles in its Baltic coast enclave of Kaliningrad if Finland and Sweden decide to join the U.S.-led NATO alliance.
(Reporting by Anne Kauranen, editing by Gwladys Fouche)