MIRANSHAH: Pakistani troops backed by attack helicopters clashed with Taliban fighters in the main town of the notorious North Waziristan tribal district on Wednesday, witnesses and officials said.

The rare clashes came one day after a bomb killed three Pakistani soldiers and although military officials confirmed troops were in action, there was no sign it was the start of a major offensive, long demanded by the Americans.

An AFP reporter heard several blasts and saw several Taliban fighters firing on Pakistan army checkposts with automatic weapons and rocket launchers in the town of Miranshah, 300 kilometres (188 miles) southwest of Islamabad.

The market shut down and the town was plunged into a black out after Taliban militants targeted an electricity transformer, the reporter said.

A security official said troops were retaliating with artillery, small and heavy weapons.

“An exchange of fire is continuing. There are no casualties on our side,” a military official in the main northwestern city of Peshawar told AFP.

The official said troops were dynamiting a private hospital, where Taliban and other militant fighters were being treated.

On Tuesday, a remote-control bomb attack near the same hospital killed three Pakistani soldiers and wounded another 15, security officials said.