PESHAWAR, Pakistan: Fighting between two militant groups has left dozens of rebels dead in part of Pakistan's restive tribal belt along the Afghan border, officials said on Sunday.

The violence began in Tirah valley in the Khyber tribal region three days ago after members of the Tariq faction of the Pakistani Taliban, who operate in Khyber, captured a building belonging to the pro-government group Ansar-ul-Islam.

"The Ansar-ul-Islam group re-took their centre after intense fighting, which according to our information has so far killed 30-40 militants on both sides," a senior local administration official told AFP.

A senior security official confirmed the approximate death toll and said fighting was ongoing. The area is cut off to journalists and aid workers so it was not possible to confirm the death toll independently.

The administration official said Ansar-ul-Islam are led by local commander Munsif Khan and oppose the homegrown Islamist militia Lashkar-e-Islam, who frequently clash with Pakistani troops.

Taliban and Al-Qaeda-linked militants have carved out strongholds in Pakistan's semi-autonomous tribal belt to plot attacks on Pakistani, Afghan and Western targets.

Pakistan came under huge US pressure to do more to destroy militant sanctuaries after US Navy SEALs found and killed Al-Qaeda leader Osama bin Laden in the Pakistani military town of Abbottabad on May 2, 2011.