28,000 Pakistani troops to mount S. Waziristan attack

Nearly 28,000 Pakistani troops have massed in the country's restive northwest, ahead of another offensive against pro-Taliban militant strongholds in the area.

The Pakistani army said it was waiting for Islamabad's go-ahead for the operation to be launched.

Pakistani Interior Minister Rehman Malik warned earlier of an imminent ground offensive in South Waziristan.

This comes as Pakistani war planes have been pounding militant hideouts in South Waziristan, near the Afghan border.

A Pakistani intelligence official said 31 militants were killed in the air raids.

Over the past week, at least 50 people have been killed in terrorist attacks across Pakistan.

In the latest incident, 22 people were killed in an attack on the army headquarters in the city of Rawalpinidi.

Islamabad says pro-Taliban militants in the country's northwest are behind the attacks.