KAZEMAYN, Iraq: More than 650 mourners of Al-Imam Musa bin Jafar Al-Kazem (p) were martyred and at least 355 injured on Wednesday, Rajab 25, after a stampede was sparked by a deadly mortar and rocket strike on his holy shrine in Kazemiyah, Baghdad, many of them drowning after falling off Al-Aaimmah bridge which they were crossing to reach the sacred mausoleum, security sources said.

There was confusion over what caused the railing to collapse on the bridge to the city's heavily Kazemiyah district.

It was the largest single death toll since after the ouster of despot Saddam in April 2003.

Terrorists fired several mortar rounds at the holy Kazemiyah shrine, as over two million mourning devotees from across Baghdad and outlying provinces had gathered to commemorate the martyrdom anniversary of the seventh infallible imam from the holy progeny of holy Prophet (p), Musa Al-Kazem.

The US military said helicopters had fired on suspected terrorists who carried out the mortar attack on the shrine and had sent ground units to the area to assist in tracking down those responsible. A dozen individuals were detained for questioning.

Iraq health minister Jalil Shamri said several other mourners were martyred by eating and drinking poisonous food and drinks at the road leading to the holy shrine.