The talks in the Finnish capital Helsinki were the first since the three sides signed an agreement on the sidelines of NATO summit in June paving the way for the Nordic countries' drive to join the Western defence alliance.

But Turkish President Recep Tayyip Erdogan then immediately threatened to freeze their membership applications unless the two Nordic states handed over dozens of people Ankara views as "terrorists".

Erdogan's foreign policy adviser Ibrahim Kalin -- the co-chair of Turkish delegation -- said after the meeting that Finland and Sweden were receptive to Ankara's demands.

"Finland and Sweden have renewed their commitment to demonstrate full solidarity and cooperation with Turkey in the fight against all forms and manifestations of terror," Kalin's office said in a statement.

The two Nordic countries broke with decades-long of military non-alignment and asked to join NATO after Russia's February invasion of Ukraine.

Their bids have already been ratified by the United States and more than half of the 30 members of NATO. Each application must win unanimous consent from member states.

Only Turkey, member of NATO since 1952, has opposed their applications, demanding the extradition of militants from outlawed groups including the banned Kurdistan Workers' Party (PKK) and people implicated in a failed 2016 Turkish coup.

Sweden announced the first extradition of a Turkish citizen this month as part of a deal the three countries signed in Madrid in June.

But Turkey's justice minister said last week that the extradition fell far short of Stockholm's commitments under the deal.

Kalin's office said the three countries agreed to "intensify technical level cooperation" in order to make concrete progress at Friday's talks in Helsinki.

The next meeting is scheduled to be held in the autumn, according to a statement issued by Finland after the talks.

"The participants discussed the concrete steps to implement the Trilateral Memorandum and agreed that the Mechanism will continue to meet at the expert level during the autumn," said the Finnish statement.