Islamabad, July 3 (DPA) At least 28 militants were killed in a suspected US drone attack and clashes with Pakistani troops in the country's northwest, officials said Friday.

The suspected US drone fired three missiles Friday at a militant hideout in the restive tribal district of South Waziristan on the Afghan border.

The missiles reportedly hit the house of a Taliban sympathiser in Kokat Khel village of the district's Ladha area, demolishing the structure.

'According to our information, 15 people have been killed and 33 others are injured,' said a local intelligence official who spoke on the condition of anonymity.

He said local Taliban as well as foreigners - a term locally used for Al Qaeda militants of Arab origin - were among the dead and injured.

'We are trying to find out if there is any important figure among the dead,' the official said.

Taliban fighters sealed off the area after the strike as they tried to pull out people buried under the rubble.

The Ladha area is a stronghold of warlord Baitullah Mehsud, who has a $5-million US bounty on his head as an Al Qaeda facilitator.

Mehsud is believed to be responsible for a series of suicide attacks on security forces as well as civilian targets across the country that has killed thousands of people over the past two years.

Pakistani forces are preparing a ground offensive against Mehsud's estimated 15,000-strong guerrilla force.

The planned operation in South Waziristan looms as Pakistani government forces were wrapping up a more than eight-week action in Swat and three nearby districts in the adjoining North West Frontier Province.

The operation has eliminated more than 1,600 Taliban, according to the government, and pushed the rest into hideouts in pine-clad mountains from where they continue to target security forces.

A military statement said Friday that during the previous 24 hours, troops had killed 10 militants during an exchange of fire in Shah Dheri, one of the last militant strongholds that the military regained from the Taliban this week.

Three more militants died, it said, in clashes elsewhere in Swat, a scenic valley where the operation began in late April when the Taliban failed to observe a peace deal.

Separately, four members of a pro-government tribal militia died in fighting with the rebels in Dir, which adjoins Swat, while a militant commander Naeem Ullah also died, the Pakistan military said.

The military offensive enjoys vast public support in Pakistan, but analysts have warned that the tide could turn against the operations if the government fails to take care of 1.9 million people displaced by the fighting in Swat and three neighbouring districts.