"We have to assess the situation, whether something has happened that in the longer term would prevent Sweden from going ahead," Foreign Minister Pekka Haavisto told broadcaster Yle.

He added that it was "too early to take a position on that now" and that a joint application remained the "first option".

"My own assessment is that there will be a delay (in getting Turkey's approval), which will certainly last until the Turkish elections in mid-May", Haavisto added.

Danish-Swedish far-right politician Rasmus Paludan set fire to a copy of the Muslim holy book on Saturday in front of Turkey's embassy in the Swedish capital.

"Sweden should not expect support from us for NATO," Turkey's President Recep Tayyip Erdogan said Monday in his first official response to the act.

The Swedish and Finnish NATO bids must be ratified by all members of the alliance, of which Turkey is a member.

Swedish leaders have roundly condemned the Koran burning but defended their country's broad definition of free speech.

Haavisto said anti-Turkey protests in Sweden had "clearly put a brake on the progress" of the applications by Finland and Sweden to join the trans-Atlantic military alliance.

"We are on a very dangerous path because the protests are clearly delaying Turkey's willingness and ability to get this matter through parliament", he said.

Haavisto also accused the protesters of "playing with the security of Finland and Sweden".

"They are taking actions that are clearly intended to provoke Turkey," he said.

Sweden and Finland last year applied to become members of NATO after the Russian invasion of Ukraine, ending decades-long policies of non-alignment.