Sweden said Wednesday that it and Finland, two countries outside any military alliances, would help monitor the airspace of NATO member Iceland for a few months in early 2014 in what is seen as a sensitive step.

Iceland has no armed forces of its own. The United States guaranteed the North Atlantic island's defence with a permanent military presence from 1951 until 2006 under an agreement between the two countries.

But the US closed its Naval Air Station at Keflavik in 2006, and since then NATO member Norway has helped Reykjavik monitor its airspace.

"In connection with the Nordic Council of Ministers session in Helsinki today, Sweden and Finland have expressed their willingness to take part in monitoring Iceland's airspace together with Norway for the first four months of 2014," Swedish Foreign Minister Carl Bildt said in a statement.

Bildt later told the Swedish news agency TT the decision was "about solidarity with Nordic neighbours and nothing to do with NATO. And keep in mind that NATO has sought assurances that we will not be carrying out NATO missions, that is for NATO countries."

Both NATO and the parliaments in Finland and Sweden have to give the green light for the operation, though no dates have yet been set for those decisions.

While Finland and Sweden are not members of the North Atlantic alliance, the two countries cooperate closely with it and regularly take part in exercises and peacekeeping operations through NATO's Partnership for Peace programme.

While increasing NATO cooperation is sensitive in both countries, it is particularly so in Finland.

It is the only non-NATO European state bordering Russia, and its non-alignment with the military bloc is seen as an important tool for maintaining good relations with its mighty neighbour.

In June, Russian armed forces chief Nikolai Makarov issued a warning to Helsinki over its close cooperation with NATO.

"Finland's participation in NATO exercises proves that Finland is gradually joining NATO activities. Under certain circumstances this can create a dangerous situation regarding Russia's military security," Makarov said in a speech in Helsinki.

Finnish Prime Minister Jyrki Katainen has said his government will not discuss the issue of possible NATO membership during the current cabinet term, which ends in 2015.