Turkey and Hungary are the only NATO members yet to ratify Sweden's bid, more than 18 months after it applied for membership.

"I had a bilateral with my colleague the foreign minister of Turkey Hakan Fidan where he told me that he expected the ratification to take place within weeks," Sweden's Tobias Billstrom said at a NATO meeting in Brussels.

"We look forward to this being completed and no new conditions were put forward in this conversation, there were no new demands from the Turkish government."

The Turkish parliament this month started to debate Sweden's application to join after President Recep Tayyip Erdogan launched the process following a deal at a NATO summit in July.

NATO's other 29 allies, outside of Turkey and Hungary, had hoped to formally welcome Sweden into the alliance at the meeting of foreign ministers in Brussels.

But the process is still stuck at the committee level in the Turkish parliament.

Sweden and Nordic neighbour Finland had dropped their long-standing policies of non-alignment and applied to join the US-led military alliance in the wake of Russia's 2022 invasion of Ukraine.

Finland became NATO's 31st member in April.

Impatient NATO members have piled pressure on Turkey at the meeting in Brussels, with France saying the credibility of the alliance was "at stake".

Billstrom said that Hungary had reiterated its pledge not to be the last country to ratify Stockholm's membership.

"That means that it is more in the hands of Ankara than maybe of Budapest," he said.

"We expect white smoke from Budapest the moment there is white smoke from Ankara."