Robertson will become the first head of the military alliance to take part formally in talks among European Union leaders, the NATO official said.

The Scottish secretary general is due to attend the EU summit near Salonika on Saturday, after his return from a trip to the United States, to take part in discussions on the western Balkans.

The EU is trying to forge closer partnerships with Albania, Bosnia, Croatia, Macedonia and Serbia-Montenegro. And with NATO backing, the bloc has fielded its first peacekeeping mission, in Macedonia.

But EU-NATO ties have also been strained by an initiative of four EU countries -- Belgium, France, Germany and Luxembourg -- to bypass the alliance and forge deeper military cooperation among themselves.

WAR.WIRE