BEIRUT, Lebanon: Lebanon's pro-Syrian groups, Amal and Hezbollah led by parliament speaker Nabih Berri and Hasan Nasrollah respectively, criticized a United Nations report on slain former Premier Rafik Hariri's assassination, saying on Monday a more thorough investigation was needed.

In a joint statement issued here, the Amal Movement and the Hezbollah said the report released last week by German prosecutor Detlev Mehlis on Hariri's February 14 assassination "did not give the Lebanese people the truth they are waiting for."

"We believe that finding the truth necessitates more serious judicial investigation based on tangible evidence away from any political manipulation and that is why we agreed on extending the investigation commission's mission until Dec. 15," the statement said.

The groups also rejected what they called the campaign of pressure led by the US and Israel against Syria.

According to the UN report Syrian and Lebanese security officials played a role in the planning and execution of Hariri's truck-bomb killing.