The claim came as a suicide car bomber rammed his vehicle into a checkpoint in Pakistan's North Waziristan tribal region, causing an explosion that killed two police and wounded five other security officials, authorities said.
Pakistani troops are engaged in offensives against the Taliban in various areas along the lawless border with Afghanistan, fighting militants often drawn from among the local communities.
Lt. Gen. Nadeem Ahmed, who heads a special support group tasked with handling the return of people displaced by three months of fighting in the Swat Valley and surrounding areas, said he had met with nine boys rescued from the Taliban.
"They have been brainwashed and trained as suicide bombers, but the nine who I met seemed willing to get back to normal life," he told Pakistani state-run television.
Ahmed's deputy, Lt. Col. Waseem Shahid, later clarified that it had not been determined whether all the boys were being trained as suicide bombers.
"What we are saying is that they are Taliban recruits. They are trained. They could have been used for any purpose," Shahid told The Associated Press.
Ahmed said on state-run TV that the children had told him there were many more, possibly hundreds, like them.
"It seems that there are some 300 to 400 such children who the Taliban had taken forcibly or who they were training," Ahmed said.
Maj. Nasir Ali, spokesman for forces in Swat, told AP that most of the several children who had been rescued were taken from a Taliban training camp in Swat after a firefight, although some had turned themselves in later. He did not say when the rescue occurred.
"The account we are getting from these boys is that there could be many more such cases, and we believe that most of them have dispersed among the public," he said. "We have appealed, and we are appealing again and again to people, to parents that if they know any of such case, they should contact us. We promise that we will do our best to rehabilitate them."
Ahmed said that a psychiatrist would examine the children to recommend how they should be reintegrated into society.
"It will be a big challenge" to reverse the indoctrination they received, he noted.
He said the boys had sometimes been lured by offers of food, but that they had been underfed and some had fallen ill.
Militant spokesmen could not be reached Tuesday for comment on the allegations.
On Sunday, authorities in Swat's main town of Mingora presented several teenagers alleged to have been forcibly recruited by the Taliban. Seven boys, their lower faces covered to prevent them being recognized, were shown to reporters.
One, a 16-year-old Shaukat Ali, said the militants abducted him while he was playing cricket. He said they told him they wanted him to be "a warrior" and offered to pay his family for his services.
Bashir Ahmad Bilour, senior minister of North West Frontier Province where Swat is located, said that dozens of children had been rescued by security forces and ranged in age from 6 to 15.
He claimed they were being trained as suicide bombers.
"They are prepared mentally. They say that Islam is everything for them. They say they are doing it for Islam. They say they have to carry suicide attacks for the sake of Islam," Bilour told private Geo TV. "They are brainwashed to such an extreme that they are ready to kill their parents who they call infidels."
He said 15 of the children were undergoing rehabilitation at an army school in the northwestern town of Mardan.
Religious Affairs Minister Syed Hamid Saeed Kazmi on Tuesday described the recruitment of youngsters as suicide bombers to be "the most serious challenge before us," his office said in a statement.
The latest suicide attack targeted a checkpoint some two miles (three kilometers) north of Miran Shah, the main town in North Waziristan, local government official Rehmat Ullah said.
North Waziristan is proving to be a trouble spot for the army just as it is in the initial phases of an offensive against Pakistani Taliban chief Baitullah Mehsud in neighboring South Waziristan.
A militant leader in North Waziristan, Hafiz Gul Bahadur, recently pulled out of a peace deal with the government, and clashes have occurred since in that region.
On Tuesday, the decapitated body of a Pakistani police constable was discovered in the Swat town of Sangota, a sign that Taliban militants have not given up the fight for the northwestern valley, despite the nearly three-month army offensive there.
Police officer Sajjad Qazi said the constable was kidnapped a week ago, apparently by militants.
Rebuilding the police is key to government efforts to regain control of Swat, especially now that hundreds of thousands of refugees are returning home.
Separately, the army said security forces killed two suspected militants and arrested another 25, including a militant commander, in separate search and clearance operations in northwest Pakistan.
They also seized large amounts of ammunition, including dozens of mortars, rocket propelled grenades, tank rounds and thousands of machine gun rounds.
Also Tuesday, Islamabad police said they had arrested a close aide to a Swat Taliban commander on the outskirts of the capital.
Police spokesman Naeem Khan would not name the arrested man or the commander. Khan said the suspect had been involved in attacks on security forces in the Swat Valley, and that explosives and weapons seized during the arrest indicated the suspect had been planning an attack.