BUDAPEST, March 27 (Reuters) - Hungary's parliament approved a bill on Monday to allow Finland to join NATO once its application has been ratified by all 30 members of the alliance, ending months of foot-dragging by the ruling Fidesz party on the matter.

Finland and Sweden asked to join the trans-Atlantic military alliance last year in response to Russia's invasion of Ukraine. But the process has been held up by Turkey and Hungary.

Although Finland's bid has now been approved, the Swedish bill is still stranded in the Hungarian parliament.

The bill on Finland's NATO accession was passed with 182 in favour and six votes against, after Fidesz said last week it would back the motion.

Turkish President Tayyip Erdogan said last week that Turkey's parliament would also start ratifying Finland's accession. But it also held off approving Sweden's bid.

NATO Secretary-General Jens Stoltenberg has said he had urged Turkey and Hungary to ratify both applications.

A vote on Sweden's bid has not yet been scheduled in Budapest.

Prime Minister Viktor Orban's chief political aide said on Twitter on Sunday the government backed Sweden's NATO membership and "now it's up to the parliament to make a decision."

"Some MPs are concerned due to Swedish government officials making a habit of constantly questioning the state of Hungarian democracy, thereby insulting our voters, MPs & the country as a whole," Balazs Orban, who is not related to the prime minister, tweeted.

Fidesz lawmakers usually act in line the policies of Orban's government as he has tightened his grip on the party.

Hungary is currently in talks with the European Commission which has held up disbursement of vital EU funds to the country due to corruption and concerns over the government's erosion of democratic rights. Orban denies the accusations.