The Pakistani army has said it had killed 30 fighters in an air strike in South Waziristan near the Afghan border where the military launched a major offensive in October.

The strike on Saturday came as teams of co-ordinated suicide attackers struck two police stations in northwestern Pakistan, killing a local police chief and wounding four officers.

An army statement said it targeted a hide-out in the Shawal mountains on a tip-off that the fighters were hiding there.

It said 30 people were killed but provided no further details.

Shawal is believed to be one of the al-Qaida and Taliban strongholds in the area.

Gul Zareen, a police official, said the suicide attacks on police stations started within minutes of each other in the district of Mansehra.

Khalil Khan, the Mansehra police chief, was killed when an attacker blew himself up inside the town's police station, Zareen said.

In the second attack, a pair of attackers stormed a station at least 25km away in the town of Balakot, triggering a shootout that left one of the attackers dead.

Zareen said the slain attacker was wearing a suicide jacket and the second attacker fled toward nearby offices.

Officers were trying to track him down, he said.