Hungary and Turkey are the only NATO members yet to approve Sweden's bid to join the world's most powerful defence alliance.

Helsinki and Stockholm ended decades of military non-alignment and decided to join the alliance in the wake of Russia's invasion of Ukraine.

The Hungarian parliament, dominated by Prime Minister Viktor Orban's right-wing Fidesz party, ratified Finland's NATO membership Monday after months of diplomatically charged delay.

Fidesz said it will decide about backing Sweden's admission to the military alliance at a later date.

"In the case of Sweden, there is an ample amount of grievances that need to be addressed before the country's admission is ratified," Orban's spokesman Zoltan Kovacs wrote on his blog.

Kovacs said there had been "a declared and open hostile attitude" for years, accusing Swedish representatives of being "repeatedly keen to bash Hungary" on rule-of-law issues.

"Adding Ankara's woes and grievances to the mix does not leave much room to manoeuvre, at least not until the Swedes start changing their tune and help these lingering wounds heal," he said.

Turkish President Recep Tayyip Erdogan is calling for Stockholm to take tougher action against Kurdish activists Ankara considers "terrorists".

Budapest insists that it supports Sweden's NATO accession.

"However, we see the need to clear the air with Sweden in order to proceed," Kovacs added.

The Hungarian opposition has accused Orban's party of trying to put pressure on Brussels by delaying a vote.

The nationalist Orban, who nursed close relations with Russian President Vladimir Putin until the invasion, has had frequent run-ins with Brussels.

The EU member is also in talks with Brussels to unlock billions of euros in bloc funding held up over rule-of-law and corruption concerns.