Macedonian police have arrested four men in an anti-terror operation launched overnight against suspected Islamic State supporters.

Police spokeswoman Dejana Nedeljkovikj says seven homes were searched early Saturday, six in the capital Skopje and one in the western town of Tetovo.

The four have been arrested for establishing a "terrorist organization" and they will be brought before an investigating magistrate later Saturday. Police are searching for one more suspect.

A criminal court earlier this year convicted 11 people, including an imam, of terror related crimes for joining the Islamic State group and recruiting fighters for it.

At the time, authorities said 130 people from Macedonia were believed to have joined IS to fight in Syria and Iraq, and 16 had been killed.