HELSINKI (Reuters) - Joining NATO is the best option for Finland to guarantee its national security, the Finnish Parliament's defence committee said on Tuesday, ahead of Finland's official decision on whether or not to join the Western defence union in the coming days.

       Finland's membership in the North Atlantic Treaty Organization (NATO) would significantly increase the deterrent for becoming a target of Russia's aggression, the defence committee concluded in a statement.

       Finland, which shares a 1,300 km (810 mile) border and a difficult past with neighbouring Russia, is reconsidering its long-standing position to refrain from joining NATO in order to maintain friendly relations with its eastern neighbour.

       Finland's President Sauli Niinisto is expected to announce on Thursday his stance on joining NATO, a move that would mean a major shift of security policy for the Nordic country in the wake of Russia's invasion of Ukraine.

       The Parliament's defence committee provided its view on the matter in response to the government's white paper update of its foreign and security policy.

       "Membership in NATO is the best solution for Finland's security. It strengthens Finland's national defence capability with the support of the union's significant military resources," the committee's chairman and main opposition leader Petteri Orpo of the National Coalition party said.

       (Reporting by Anne Kauranen; Editing by Alexandra Hudson)