At least 14 people were killed and many more injured when a suicide bomber on a motorbike crashed into the main gate of a government office in the northwest Pakistan town of Mardan.

At least 14 people were killed and many more injured when a suicide bomber on a motorbike crashed into the main gate of a government office in the northwest Pakistan town of Mardan, officials said.

No group has yet claimed responsibility for the attack, but Pakistan is fighting Taliban and other terrorist groups in its northwest border regions, who often target government and security forces.

"It was a suicide bomber riding on a motorbike. The death toll could rise," Faisal Shahzad, district police chief told AFP.

Ali Khan, a doctor at the district headquarters hospital confirmed the death toll and placed the number of injured at "more than 40".

The blast ripped through the front entrance of a regional branch of the National Database and Registration Authority (NADRA) which is responsible for issuing ID cards.

Pakistan's army has been battling a homegrown terrorist insurgency since 2004 after the US-led invasion of Afghanistan caused militants to flee across the border where they began to foment unrest.

More than 27,000 civilians and security forces personnel have died in terror attacks since that time, according to the South Asia Terrorism Portal, a monitoring site.