A blast rattled a ceremony attended by US Ambassador to Iraq Zalmay Khalilzad in the northern Iraqi city of Tikrit on Tuesday.

The ceremony was designed to hand over a former presidential palace complex of Iraq's toppled leader Saddam Hussein, which has been used by US military, to local Iraqi authorities, a local journalist, Ali Salih, told Xinhua.

The blast was caused by a mortar round which landed some 100 meters away from the ceremony site, causing panic among the attendants, which also included US troops Commander Gen. George Casey, Salih said.

There was no immediate word on casualties, he added.

Tikrit, some 170 km north of Baghdad, is Saddam's hometown.

(Source: Xinhua)