The announcement on the ground-based air defence project comes ahead of a meeting of the defence ministers of Switzerland, Germany and Austria -- Viola Amherd, Boris Pistorius and Klaudia Tanner -- in Bern on Thursday and Friday.

They will discuss the security situation in Europe, the effects of the war in Ukraine and security cooperation between the three German-speaking neighbours.

The ministers will also sign a memorandum of understanding on their participation in the European Sky Shield Initiative, which deals with procurement, and an agreement to promote research cooperation on armaments, the Swiss government said in a statement.

"With the signing of the MoU, Switzerland and Austria are joining the 17 European states already participating in ESSI," the statement said.

"It is in Switzerland's interest to gear its security and defence policy more consistently towards international cooperation, and to increase its contributions."

Austria, also a neutral country, announced on Saturday its intention to join the ESSI, with Chancellor Karl Nehammer insisting that decision did not call into question Austria's neutrality.

- Neutrality maintained -

Switzerland's long-standing position has been one of well-armed military neutrality, and the landlocked country of 8.8 million people has mandatory conscription for men.

But Switzerland's tradition of neutrality has been hotly debated since Russia's invasion of Ukraine in February 2022.

While the wealthy Alpine country, which is not a member of the European Union, has followed the bloc's lead on sanctions targeting Moscow, it has so far shown less flexibility on its military neutrality.

Despite pressure from Kyiv and its allies, Switzerland has refused to allow countries that hold Swiss-made weaponry to re-export it to Ukraine.

Switzerland said each country could control the extent of its participation in the Sky Shield project.

"It is possible for neutral states to participate in many areas," the government said.

"Switzerland and Austria have set out their terms regarding neutrality in an additional declaration, stating, for example, that they will not participate or be involved in international military conflicts."

Led by Germany, 17 European nations including Britain, Belgium, Finland, Hungary, the Netherlands and Sweden have banded together on the ground-based air defence under the ESSI project.

The Sky Shield system would involve joint procurement for short-, medium- and long-range systems, including the German-made Iris-T, the American Patriot and the US-Israeli Arrow-3 missiles.

But France, Italy and Poland have not signed up to the project, with Paris arguing instead for an air defence system using European equipment.