Lithuania has warned Turkey that its delay in approving Sweden and Finland’s applications to join Nato is not just putting their security at risk but that of the entire Baltic region.

Gabrielius Landsbergis, Lithuania’s foreign minister, said he had told Mevlüt Çavuşoğlu, his Turkish counterpart, that the situation in the entire Nordic-Baltic region, where many countries border Russia, was highly sensitive after Moscow’s full-scale invasion of Ukraine.

“We’re talking with our good friends in Turkey that the delay affects our security directly, and therefore we would very much like it to be resolved,” he told the Financial Times.

Sweden and Finland’s applications to join the western military alliance have been approved by 28 of the 30 existing Nato members, with Hungary saying its parliament should ratify early next year.

Turkey is the biggest holdout, with President Recep Tayyip Erdoğan saying that Sweden in particular needs to cut ties with Kurdish groups that Ankara labels as terrorists as well as speed up extraditions of suspected criminals.

Sweden’s new centre-right government has made Nato membership its number one foreign policy priority, and foreign minister Tobias Billström said in a separate interview that it had brought a “new tone” to discussions with Ankara.

Jens Stoltenberg, Nato secretary-general, said of Sweden and Finland’s membership bids that “it is time to finalise their accession process and welcome them as full-fledged members of our alliance”.

Stoltenberg, who has been involved in negotiations between the two countries and Ankara, visited Erdoğan this month to make clear that Ankara’s ratification of the bids was necessary.

“I have conveyed the message to Turkey,” he said on Friday. “I am confident that all allies will ratify. I will not speculate about exactly when, but the sooner the better.”

Landsbergis said: “A lot of countries are tapping their fingers on the table, waiting for the decision to be made. It’s about Lithuania, it’s about Latvia and Estonia, definitely about Sweden and Finland, but also Denmark, Norway and even Iceland. We’re all connected.”

The Suwalki Gap on Lithuania’s border with Poland, where Russia through its Kaliningrad exclave is just 65km from the western border of its ally Belarus, is one of Nato’s biggest vulnerabilities. The alliance’s military planners worry that a lightning strike by Russia in this region could cut off the Baltic states from the rest of Europe.

Lithuania’s foreign minister said he was keen for Sweden and Finland to become Nato members quickly so that they and the Baltics could discuss collaboration such as “more air defence projects that we can undertake with Finland, more maritime co-operation with Sweden”.

Ankara this week summoned the Swedish ambassador to condemn an incident in which images that “insulted President Erdoğan” were projected on to the Turkish embassy in Stockholm.

Speaking before the incident, Billström hailed Swedish prime minister Ulf Kristersson’s meeting with Erdoğan in Ankara earlier this month and said there should be a return visit from Turkish officials to Stockholm in December.

“It showed a good spirit of co-operation between our countries. The process as we see it will be moving forward,” Billström added, although he did not set a timeframe for when Turkey might ratify the Nato membership.

Some experts fear it could be after Turkish presidential elections next June and July, something that would cause dismay in Sweden, Finland and the Baltics.

Billström repeated that Sweden would not give any financial or military support to two Kurdish groups that Ankara regards as terrorists but have been used by the US and allies in the fight against Isis.

He stressed that Sweden and Finland’s Nato accession would “definitely bring greater stability to this part of Europe” and that Stockholm was in close contact with all the countries in the Baltic Sea region apart from Russia.

“I know the new government in Sweden are putting a lot of effort into this. They’re optimistic, and that’s why I’m optimistic,” said Landsbergis.

Additional reporting by Ayla Jean Yackley in Ankara and Henry Foy in Brussels