A suicide bomb attack outside a government office in northwest Pakistan on Tuesday left at least one person dead and 17 injured, officials said.

The attack took place in Mardan, about 50 kilometres (30 miles) 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."

Faisal Shahzad, district police chief, confirmed the incident and said the toll stood at one dead and 17 injured, two of whom were in critical condition.

He said the bomber arrived at the office on foot and opened fire with a gun before detonating his explosives vest at the office gate.

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

No one immediately claimed responsibility for the attack. 

But the Pakistani Taliban and other Islamist 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.