Government forces have stepped up attacks in the northwestern Orakzai and Khyber regions on the Afghan border in recent weeks after largely clearing Taleban strongholds in other areas. "Fighter jets bombed and destroyed five of their hideouts early in the day, killing 15 militants and wounding 25," said government official Nauman Khan.

Pakistani troops also used artillery to target militants' positions overnight in the same region. Security officials said 25 militants were killed in the barrage.

A Taleban spokesman in Orakzai, who identified himself as Hafiz Saeed, confirmed the air strikes on their positions but said only three of his comrades were killed and eight wounded. The military says several hundred Taleban fighters have been killed in Orakzai in recent weeks but there has been no independent confirmation of that. The Taleban usually dispute the army's accounts of engagements.

Nuclear-armed Pakistan joined the US-led campaign against militants after the Sept. 11, 2001, attacks on the United States.

A year ago, the security forces began a series of sustained offensives and managed to clear many fighters from the Swat Valley, northwest of Islamabad, and from South Waziristan and Bajaur on the Afghan border.

In recent weeks, the army has turned its attention to the Orakzai and Khyber regions, where many fighters are believed to have taken refuge from the earlier offensives.

Despite losing ground to security forces, the militants have shown the ability to hit back and have carried out a wave of bomb attacks, killing hundreds of people, mainly in the northwest.

On Thursday, militants attacked a police vehicle in Orakzai's neighboring town of Hangu, wounding three policemen, security officials said. One militant was killed in retaliatory fire.

Thursday's attacks in Orakzai came amid reports that Fazlullah, the leader of the Pakistani Taleban in Swat, might have been killed in a clash in Afghanistan's Nuristan province.

A Pakistani security official said he was reported to be in Nuristan along with his family, but he did not know if there was any clash.

A self-styled cleric, Fazlullah has been on the run since a military offensive launched in Swat in April last year. In a BBC interview in November, Fazlullah said he had escaped to Afghanistan.