A suicide bomb attack outside a government office in northwest Pakistan on Tuesday injured at least eight people, two of whom were in critical condition, officials said.

A suicide bomb attack outside a government office in northwest Pakistan on Tuesday injured at least eight people, two of whom were in critical condition, officials said.

The attack took place at the Excise and Taxation office in Mardan, about 50 kilometers northeast of the region's main city of Peshawar.

Shahid Khan, a senior local police official, told AFP: "It was a suicide attack, the target was the office of Excise and Taxation.

"All eight injured people have been taken to hospital, two of them are critical."

Faisal Shahzad, district police chief, confirmed the toll and said the bomber arrived at the office on foot and opened fire with a gun before detonating his explosives vest at the gate of the office.

"Eight to ten kilograms of explosive were used," he said.

No one immediately claimed responsibility for the attack.

But the Pakistani Taliban and other extremist groups regularly target military and civilian installations as part of an insurgency, which has claimed tens of thousands of lives since it began in 2004.

Tuesday's attack comes weeks after a Taliban suicide bomber targeted Christians in a park in the eastern city of Lahore at Easter, killing more than 70 people, including many children.