"I look forward to raising Finland's flag at NATO HQ in the coming days. Together we are stronger and safer," Stoltenberg wrote on Twitter.

After months of delays, Turkey's parliament on Thursday removed the last hurdle for Finland by becoming the last member of the US-led military alliance to ratify its application.

Stoltenberg said in separate statement that "Finland has highly capable forces, advanced capabilities, and strong democratic institutions."

"So Finland will bring a lot to our alliance," he said.

NATO foreign ministers are meeting at the alliance's headquarters in Brussels next week, when it is expected the membership could be formalised.

Russia's invasion of Ukraine last year upended European security and pushed Finland and its neighbour Sweden to drop decades of non-alignment and seek to join NATO's protective umbrella.

Stockholm application remains stuck, however, because of ongoing resistance from both Turkey and Hungary.

But Stoltenberg insisted that "all allies agree that a rapid conclusion of the ratification process for Sweden will be in everyone's interest,"

"I look forward to also welcoming Sweden as a full member of the NATO family as soon as possible," he said.