Beirut:The assassination of Lebanese former prime minister Rafiq Hariri is extremely complex and there will be no deadlines in issuing indictments on the case, Antonio Cassese of the UN-backed Special Tribunal for Lebanon told the press.

"All acts of terrorism are much more complicated than war crimes, crimes against humanity and genocide," he said.

Cassese arrived in Lebanon on Monday for a week-long visit aimed at gathering information for the ongoing investigation, but admitted in the difficulties behind investigating political assassinations.

"All acts of terrorism are much more complicated than war crimes, crimes against humanity and genocide," he said.