Greek authorities say protesting Communist party members have blocked a northern highway for hours to prevent an Albanian military convoy from travelling toward a NATO exercise in Romania.

Dozens of protesters prevented the 19 military vehicles from passing through a highway toll booth near the northern Greek town of Kozani for more than four hours Friday.

The protesters let all other traffic through while holding up a banner reading "NATO killers go home."

The Albanian convoy of military trucks and buses took an alternative route.

Albania's army General Staff said in a statement that the troops were going "toward the final destination."

"All the troops enjoy good health and are being accompanied under tight security steps from the Greek military and civil authorities," said the statement sent to The Associated Press.

Some 2,000 troops and more than 500 vehicles are heading to the Cincu training area in central Romania for the alliance's Noble Jump drill.

Participating countries include Britain, Germany, the Netherlands, Spain, Poland, Norway and Albania.