ISLAMABAD, Oct. 30 (Xinhua) -- Local tribesmen in northwestern Pakistan's tribal region on Thursday opened fire at the suspected U.S. drones, and forced them return back to Afghanistan, local television reported.

    The U.S. drones made flights in different parts of North Waziristan tribal agency, and the tribesmen targeted drones with heavy and automatic weapons and forced them to go back Afghanistan, local Geo TV said.

    U.S. drones have conducted a series of cross-border strikes inside Pakistan recently, blaming Pakistan's inability to curtain Taliban insurgency in the tribal regions.

    Suspected U.S. drones fired missiles targeting local militants in South Waziristan tribal region who gathered to offer prayers on Sunday night, killing at least 20 people.

    Pakistan on Wednesday summoned U.S. ambassador to Pakistan and expressed its strong protest over the missile strikes by American drones in the country's tribal regions.

    "It was underscored to the ambassador that the government of Pakistan strongly condemns the missile attacks, which resulted into the loss of precious lives and property," said a statement from Pakistan's foreign ministry.

    "It was emphasized that such attacks were a violation of Pakistan sovereignty and should be stopped immediately," the statement said.

    Media reports said that the U.S. drones based in Afghanistan have carried out 34 strikes and intrusions into Pakistan in the last seven months.