The prime minister of Sweden has warned against delinking his country’s Nato membership bid from Finland’s, after the alliance acknowledged for the first time that the two might have to join separately owing to Turkey’s obstruction.

Ulf Kristersson said in an interview that for strategic reasons, the two membership applications should be ratified at the same time.

“The very close military co-operation between Sweden and Finland before we are Nato members would be very much complicated by us being divided as members,” he told the Financial Times.

“Finland and Sweden are security providers,” he added. “We have capabilities in our part of the world that all Nato countries will benefit from, including Turkey.”

Stockholm and Helsinki closely co-ordinated their bids, handing them in together last year. But Turkish president Recep Tayyip Erdoğan raised objections, saying he wanted Sweden to take a clearer stance against Kurdish activists that he considers to be terrorists.

The three countries had been making progress in negotiations to resolve the dispute but Ankara suspended them in January after a Koran was burnt in front of Turkey’s embassy in the Swedish capital.

Both countries need all 30 existing Nato members to ratify their accession. All but Turkey and Hungary have done so, and Ankara has suggested that it could ratify Finland before Sweden. Budapest said it would ratify both in the coming weeks.

Nato secretary-general Jens Stoltenberg earlier this month openly acknowledged the possibility of the two joining separately with Finland going first.

Kristersson, however, is continuing to insist that they are admitted together. “We started the process together and we have conducted it together, and we want to complete it together,” he said. “There are very, very good reasons for ratifying us at the same time before Vilnius” — a reference to the Nato summit being held in the Lithuanian capital in July.

He warned of the consequences if Turkey failed to ratify Sweden’s membership by the Vilnius summit. “I think it would be bad for Sweden, bad for our region, bad for Nato and bad for Sweden’s ability, together with Finland, to provide security in the midst of a war in our neighbourhood,” he said.

The prime minister, who was speaking on the sidelines of the Munich Security Conference, said that in all his talks at the MSC he had found “enormously strong support among other leaders in the EU and among Nato allies as well” for the two countries joining together.

Asked how he would react if Finland didn’t wait for Sweden and joined on its own, he said: “I’m not really planning for that.” But he added: “Every country has to make its own decision.”

His Finnish counterpart, Sanna Marin, appeared to endorse his line. “It’s . . . in the interest of Nato that Sweden and Finland join simultaneously,” she said during a podium discussion in Munich. “We prefer and want to join together.”

Kristersson said Sweden had delivered on all points of a trilateral memorandum between Finland, Sweden and Turkey agreed in June that sets out a list of steps Stockholm would take to secure Ankara’s support.

These include distancing itself from a Kurdish militia, lifting an embargo on weapons exports to Turkey and stressing it would work to combat terrorism.

He said a final step comes on March 2 when the Swedish government decides on new laws for fighting terrorism. “It’s such a big piece of legislation that we actually had to change our constitution as of January 1 to be able to introduce it,” he said.

Sweden is also seeking to win goodwill from Turkey by stepping up its supplies of humanitarian aid to areas affected by the devastating February 6 earthquake. He said his government had decided to send an additional €4.5mn in medical supplies and equipment, as well as 500 units of emergency housing, capable of accommodating 2,500 people.

He added that Stockholm was also using its rotating presidency of the EU to help organise a donors’ conference next month in Brussels designed to raise money for those affected by the earthquake.

Additional reporting by Henry Foy in Brussels and Richard Milne in Oslo