Beirut - Lebanon's Internal Security Forces (ISF) Director General Ashraf Rifi said Saturday all active units were on highest alert as the Special Tribunal for Lebanon was scheduled to open Sunday The Hague.

Rifi said it was necessary to "tighten the grip on security measures and to set up checkpoints to preserve law and order." The ISF and the armed forces would coordinate efforts countrywide.

Soldiers were seen taking up positions at strategic points in Beirut.

The special tribunal will try suspects in the 2005 assassination of former Lebanese premier Rafik Hariri.