Islamabad - A suicide bomber blew himself up on Friday outside the office of a senior police officer, killing five policemen and four civilians in Pakistan's restive North-West Frontier Province (NWFP), officials said.

Deputy Inspector General of Police Akhtar Ali Shah said the attack against a vehicle of his security escort took place when he was about to leave his office in Mardan, some 50 kilometres north-east of provincial capital Peshawar.

"From evidence collected from the site it appears to be a suicide attack," he told English-language Dawn news channel. "The skull and limb of the suspected suicide bomber have been found."

His deputy Iqbal Khan said the bomber, who was on foot, detonated the explosives when he was "challenged by an officer on duty."

"Four policemen and four civilians died on the spot while another police officer succumbed to injuries at the hospital," he added.

Twelve people were injured in the incident.

No one has claimed the responsibility but the NWFP and rest of the country has seen intensified attacks by Taliban militants targeting security officials and political leaders.

The bombing campaign has created an atmosphere of fear and uncertainty, driving away foreign investors, and leaving the country's economy crippled.

Pakistan's foreign reserves have dropped some 75 per cent over the last 12 months, from 18 billion dollars to around 4.3 billion. At the same time, the rupee has weakened by more than 27 per cent against the dollar.

This forced the nuclear-armed Islamic country to seek an IMF bailout program to avert default on its external payments. The first round of talks between the sides concluded on Thursday in Dubai.