KANO, Nigeria (AFP) - At least two people were killed when a car exploded at a police station in Potiskum, north-east Nigeria, an officer told AFP.

The blast at the facility attached to the Potiskum Area Command at about 3.30pm involved a driver and vehicle which had earlier raised suspicions at a checkpoint outside the city.

A policeman was escorting the driver in his vehicle before planned questioning.

"It was while they were at the gates of the police station undergoing security checks that the car exploded," said the officer, who asked not to be identified.

"The policeman and the driver have been confirmed dead but details of other casualties are not clear yet."

Potiskum has been targeted on previous occasion by Boko Haram, the Sunni Islamists who have been fighting a bloody insurgency in north-east Nigeria since 2009.

On Nov 10, a suicide bomber disguised in school uniform blew himself up at morning assembly before lessons at the Government Comprehensive Senior Science Secondary School, killing 58. More than 100 were injured.

A week earlier, 15 people were killed and some 50 others injured in a suicide bombing targeting a major Shia Muslim festival.

On Dec 31, seven people were killed when a bus exploded in a village 60km from the city, which is the commercial capital of Yobe state.

In the latest explosion, local resident Kamilu Nasir said the explosion rocked the whole area.

"I was inside my house listening to the radio when I heard a loud explosion that made my house vibrate.

"I rushed out only to see the police station on fire and people wailing in fright," Nasir said.