ISLAMABAD - Missiles fired from unmanned U.S. planes hit a training camp and communication centre run by a Taliban leader close to the Afghan border, killing 17 people and adding to pressure on the insurgents in a region also being targeted by the Pakistani military.

The two attacks in South Waziristan took place as U.S. Marines on the other side of the border pressed ahead with a major offensive aimed at reversing Taliban gains in southern Afghanistan eight years after the Islamist rulers were ousted from power by the American-led invasion.

The drone attacks Friday were the latest of more than 40 believed to have been be carried out by the United States against militant targets in the border area since last August. Washington does not directly acknowledge being responsible for the attacks, which kill civilians as well as militants and contribute to anti-US sentiment in nuclear-armed Pakistan.

Islamabad officially protests the strikes as violations of its sovereignty, but most experts believe the government secretly endorses them and likely provides the United States with intelligence on possible targets.

South Waziristan is a mountainous, remote region where al-Qaida and Taliban militants have long held sway. It is the stronghold of Baitulllah Mehshud, the leader of Pakistani Taliban. He and his followers have been blamed for some of the bloodiest suicide attacks to hit Pakistan in recent years.

In one attack Friday, two missiles struck an abandoned seminary in the village of Mantoi that was being used by militants from Mehsud's group for training, two intelligence officials said. In the other strike, one missile hit an insurgent communications centre run by Mehsud in the nearby village of Kokat Khel, they said on condition of anonymity because they were not authorized to speak to the media.

In total, 17 people were killed and 27 others were wounded, they said.

However, Maulvi Noor Syed, an aide to Mehsud, told The Associated Press that three Taliban fighters died in the strikes. "We lost only three mujahedeen (holy warriors) in today's American missile attack," Syed said. "These attacks cannot cause any damage to us."

Access to the region is strictly controlled, and the death toll could not be independently verified.

In recent weeks, Pakistan has fired mortars and dropped bombs on militants linked to Mehsud in South Waziristan, saying it is softening up the region for a ground offensive. The operations follow a major push in the nearby Swat region that the military claims has killed more than 1,000 militants and driven them out.

Waziristan is more than 621 miles (1,000 kilometres ) along from the stretch of border opposite Afghanistan's Helmand province, where some 4,000 U.S. Marines were deployed Thursday. Pakistan's army said it was deploying extra troops along the stretch to stop Taliban fleeing the offensive.

The Obama administration wants to see Pakistan do more to fight militants on its side of the border, believing the insurgents are supplying arms and recruits for the fight against US and NATO troops in Afghanistan. It would like to co-ordinate operations to squeeze the militants but there is little evidence of this happening so far.

In neighbouring North Waziristan on Friday, Pakistani warplanes bombed suspected militant hide-outs, killing at least four insurgents and wounding seven others, two more intelligence officials said. Those airstrikes hit targets where Taliban fighters killed 16 government troops in an ambush earlier this week, the officials said, also speaking on condition of anonymity because they were not authorized to speak to the media.

Also Friday, local residents found the body of a man accused by the Taliban of spying for the United States close to the North Waziristan town of Mir Ali. Explosives had been attached to his body and then detonated, said police officer Akhtar Ullah.

"This is the fate everyone will meet for spying on America," read a note attached to the body.

Also in North Waziristan, leaflets distributed by the Taliban after prayers at mosques in Miran Shah warned people in the region Friday not to visit government offices and security posts or join any government-sponsored tribal militias to fight the insurgency. The punishment would be death, the leaflets said.