A suspected missile attack on a militant hideout in a remote area of northwestern Pakistan near the Afghan border Tuesday killed over 20 insurgents, security officials said.

Several militants were also wounded when three missiles allegedly fired from Afghanistan destroyed a training facility, housed in a big mud-brick seminary, in the border village of Mami Rogha, 25 miles west of Miran Shah, the main town in North Waziristan, two intelligence officials said.

The officials spoke on condition of anonymity because they were not authorized to comment to the media.

Pakistan army spokesman Maj. Gen. Waheed Arshad claimed, however, that the explosions were caused when bombs the militants were making at an isolated compound exploded accidentally. He said more than 20 were killed.

"According to the information I have received from military sources, the blast happened when these militants were making bombs," he told The Associated Press, without elaborating.

One local intelligence official said between 20 to 25 militants were killed when three missiles hit the hideout.

"We have received reports that the missiles came from Afghanistan," said the official, without offering any evidence to back up his claim.

Another Pakistani intelligence official in Islamabad, who also requested anonymity, said the compound lay about two miles inside Pakistan and is surrounded by thick forests.

He said nearly three dozen militants were sitting in an open area of a madrassa, or Islamic seminary, when the attack happened, but could not confirm exactly who fired the missiles, although both officials claimed the missiles came from Afghanistan.

The U.S. military in Afghanistan said it had no reports of missiles being fired across the border.

"I am not aware of any reports of any missiles being fired from Afghanistan into Pakistan," said Lt. Col. David Accetta, spokesman for the U.S.-led coalition in Afghanistan.

"Pakistan is a sovereign nation, and we respect sovereignty," he said.

Taliban and Al Qaeda fighters are believed to shelter in North Waziristan, where last September Pakistan, a key ally in the U.S.-led war on terrorism, signed a peace deal with Taliban sympathizers as part of its bid to bring the lawless region under control.

Critics, however, say the agreement may have given a freer hand for militants to stage attacks on U.S. and NATO forces across the border in Afghanistan.

Several raids on suspected terror targets in Pakistan have apparently been launched from Afghanistan.

In January 2006, a CIA Predator drone hit houses in a Pakistani border village in Bajur, a tribal region north of Waziristan, where Al Qaeda No. 2 Ayman al-Zawahri was expected to visit, Pakistani intelligence officials said. Al-Zawahiri escaped injury but 13 other people were killed.

The U.S. government never confirmed its involvement in that strike.

In December 2005, a Hellfire missile allegedly fired by an unmanned American warplane killed an Egyptian Al Qaeda figure, Hamza Rabia, in North Waziristan. Pakistan's army, however, maintained that Rabia had died in a bomb-making accident.

Pakistani forces have also raided suspected militant hideouts using U.S.-supplied helicopters.