Western officials had hoped Erdogan would soften his position on the diplomatically charged issue after he secured a hard-fought re-election last month.

But Erdogan signalled no major shift in comments that were released by his office while Turkish and Swedish officials were locked in last-minute negotiations in Ankara.

"Sweden has expectations. It doesn't mean that we will comply with them," Erdogan was quoted as saying.

"In order for us to meet these expectations, first of all, Sweden must do its part."

Sweden and its Nordic neighbour Finland ended decades of military non-alignment and applied to join the US-led defence bloc in response to Russia's invasion of Ukraine.

Turkey and fellow NATO member Hungary ratified Finland's membership this year.

But both countries' parliaments have yet to approve Sweden's entry.

Unanimous backing is needed for new countries to secure the guarantees afforded by the world's most powerful defence alliance.

- 'Let's get that done' -

US President Joe Biden pressed Erdogan about Sweden during a call he placed a day after the Turkish leader extended his two-decade rule until 2028.

Ankara hopes to win US congressional approval of a major defence package that could substantially modernise Turkey's ageing fleet of fighter jets.

Biden directly linked the F-16 fighters' sale with the Swedish bid for the first time.

Erdogan "still wants to work on something on the F-16s. I told him we wanted a deal with Sweden, so let's get that done", Biden told reporters after the call.

And NATO Secretary General Jens Stoltenberg personally discussed the bid with Erdogan in Istanbul ahead of an alliance summit in Lithuania in July.

Erdogan noted that Stoltenberg's visit coincided with a protest held in Stockholm by Kurdish supporters of a group recognised as a terrorist organisation by Ankara.

Turkey is pushing Sweden to ban and crack down on such rallies.

"There are rights given to (Sweden's) law enforcement under the constitution. Use those rights. If you don't deal with it, we cannot (say yes) at the summit in Vilnius," Erdogan said.

- 'Progress has been made' -

Sweden has already taken a series of measures aimed at appeasing Turkey's concerns.

It has agreed to extradite a self-proclaimed supporter of the Kurdish militants who was convicted of drug trafficking and arrested in Sweden in August last year.

Turkey "was able to raise some concerns that it had. Finland and Sweden have both addressed those concerns and, in our judgement, addressed them appropriately and effectively", US Secretary of State Antony Blinken said this week.

"And that's what we're looking to see take place over the coming weeks."

Wednesday's lower-level talks in Ankara ended with an agreement for the two sides and Finland to meet again at an undisclosed time.

"My chief of staff is at the meeting. I just spoke to him and he could inform that the meeting took place in a constructive atmosphere," Stoltenberg told reporters in Brussels.

"So progress has been made and we will continue to work for the ratification of Sweden as soon as possible."

Turkey's parliament has returned from its election campaign break and is scheduled to be in session until the two-day Vilnius summit starts on July 11.

Hungary's parliament has extended its current session -- which had been due to end on Thursday -- until July 7.

Its "extraordinary summer session" is officially focused on adopting a budget but could also take up the Swedish ratification vote.

Hungarian Prime Minister Viktor Orban and Erdogan both enjoy good working relations with Russia's Vladimir Putin.

Orban's ruling party scheduled a Finnish ratification vote in the Hungarian parliament just moments after Erdogan lifted his own objections in March.