A probe, whose report was submitted to Prime Minister Yousaf Raza Gilani, was done by a team of experts headed by the Federal Investigation Agency director general, Dawn reported Monday.

The report suggested that 600 kilograms or nearly 1,325 pounds of high-intensity explosive materials, RDX and TNT, were transported in a truck to be used in the attack.

It said the vehicle used by the sole suicide bomber rammed the security barrier when it was stopped for security check. Later the vehicle caught fire, triggering the explosion.

Gilani told reporters in Lahore the prime minister's house was the original target but the attackers were deterred because of the tight security in the area ahead of a dinner gathering of the country's leaders, other reports said.

The hotel attack killed at least 53 people, including the Czech Republic ambassador, two Americans and one Vietnamese national.

A separate Dawn report said questions were being raised as to how so much of high-quality explosives could find their way into a high security area.