Stoltenberg arrived in Ankara 10 days after Turkey was hit by a massive earthquake that has claimed nearly 40,000 lives across the country's southeast and parts of Syria.

"In your time of need, NATO stands with Turkey," Stoltenberg said.

But he also stressed the urgency of Ankara dropping its resistance to the Nordic neighbours' bids to join the Western defence alliance.

"I continue to believe that the time is now to ratify both Finland and Sweden," Stoltenberg said after talks with Turkish Foreign Minister Mevlut Cavusoglu.

Finland and Sweden dropped decades of military non-alignment and applied to join the US-led defence alliance in response to Russia's invasion of Ukraine.

Turkey and Hungary remain the only members of the 30-nation alliance that have failed to ratify the two bids by votes in parliament.

All 30 states must approve a new country's membership. The Hungarian legislature is expected to approve both bids by March.

Turkey has signalled it is ready to receive Finland into the alliance -- but not Sweden.

"We could evaluate Finland's NATO membership process separately from Sweden," Cavusoglu said on Thursday.

"Turkey's position on the membership of the two countries has been clear and unambiguous from the beginning."

Turkish President Recept Tayyip Erdogan's main complaint has been with Sweden's refusal to extradite dozens of suspects that Ankara links to outlawed Kurdish groups and a 2016 coup attempt.

"Both can be ratified now," Stoltenberg said. "But the main issue is not that they are ratified together. The main issue is that they are ratified as soon as possible."