Nato membership for Finland and Sweden is “a top priority”, the military alliance’s chief Jens Stoltenberg said, as he urged members Turkey and Hungary to urgently ratify the Nordic countries’ accession.

Mr Stoltenberg told a news conference with Finnish prime minister Sanna Marin in Helsinki that progress is being made on securing membership for the two countries but did not disclose details.

“I am absolutely confident that both Finland and Sweden will become members of Nato,” he added.

“My message has been for a long time… that time has come to finalise the ratification process. The time is now to ratify in both Budapest and in Ankara,” Mr Stoltenberg said.

He repeated that both Finland and Sweden fully meet Nato’s entry criteria and “have delivered on what they were supposed to do” after they applied to join the alliance in May.

Ms Marin hinted that slowing down the accession process for the two countries risked eroding Nato’s credibility and its open door policy for new members.

Nato requires unanimous approval from its existing members to admit new ones. Turkey and Hungary are the only nations in the 30-member military alliance that have not formally endorsed Sweden and Finland’s accession.

Mr Stoltenberg, who is expected to step down in October after eight years at the post, said Turkey has agreed to resume talks with Finland and Sweden on their membership bids in Brussels early next month to iron out obstacles and issues that Ankara has, especially with Sweden.

He said the Hungarian Parliament “has made it clear” that it would deliberate ratification in a few days and expressed hope that a positive vote would come soon.

Finland’s 200-seat Parliament is set to approve legislation to allow the country to join Nato.