WASHINGTON (AFP) - Nato said on Wednesday (June 1) it will hold talks involving Turkey, Finland and Sweden in hopes of ending Ankara's opposition to the Nordic nations joining the alliance ahead of a summit this month.

Secretary-General Jens Stoltenberg said he would convene senior officials from the three nations in Brussels in the coming days "to ensure that we make progress on the applications of Finland and Sweden to join Nato."

"My intention is to have this in place before the Nato summit" in Madrid starting on June 28, Stoltenberg said on a visit to Washington.

"Finland and Sweden have made it clear that they are ready to sit down and to address the concerns expressed by Turkey," Stoltenberg told a joint news conference with US Secretary of State Antony Blinken.

Sweden and Finland have historically tried to steer clear of angering nearby Russia but shed their reluctance to join Nato after Moscow's invasion of Ukraine - which had unsuccessfully sought to join the alliance.

Russian President Vladimir Putin "wanted less Nato. He is getting more Nato," Stoltenberg said.

But all 30 Nato members need to agree to admit a new member and Turkey has voiced objections, citing the presence in the two Nordic nations of militants from the PKK, the Kurdish separatist group considered terrorists by Ankara.

Stoltenberg said that the two nations and Nato took the PKK issue "very seriously."

"We know that no other Nato ally has had suffered more terrorist attacks than Turkey," Stoltenberg said.

Blinken reiterated that he remained "very confident" that Nato will "move forward" with the membership of the two nations.

He appeared to play down linking the membership to Turkey's desire to buy F-16 fighter jets, as some pundits believe Ankara is holding out for concessions.

"These are separate questions. We have a longstanding and ongoing defence relationship with Turkey as a Nato ally," Blinken said.

"We'll continue to work through cases as they as they arise with regard to systems that Turkey seeks to acquire," Blinken said.

The United States expelled Turkey in 2019 from development of the state-of-the-art F-35 in retaliation for Ankara's purchase of an advanced air defence system from Russia.

But Turkey's image has risen in the United States through its drones that it has sold to Ukraine, even as Ankara avoids sanctions on Russia.