ISLAMABAD, Jan. 3 (Xinhuanet) -- Pakistan has lodged protest with Afghan government and US-led coalition forces in Afghanistan over the killing of one of its paramilitary soldiers and injuring three others by firing from Afghan territory, a Pakistani military spokesman said on Monday.

    The soldier was killed and three others injured on Sunday in Pakistan's North Waziristan tribal region bordering Afghanistan, Military Spokesman Major General Shaukat Sultan Monday told a local television.

    "We have lodged written and verbal protest but have not received any response," the spokesman said.

    "We consider it a hostile fire and that is why our troops also returned fire," he said.

    He said some 25-30 mortars were fired in the Pakistani territory. "The firing stopped after Pakistani border troops returned fire," he said

    The spokesman said it is not clear if the mortars were fired from US-led forces or suspects, adding that such incidents usuallydo not happen.

    Pakistan has deployed thousands of troops along its border with Afghanistan to block attempts by Taliban and al-Qaeda suspects into Pakistani territory.

    The cross-border firing coincided with the crash of an unmannedspy plane in the Pakistani territory on Sunday.

    But the Pakistani military spokesman ruled out any linkage of the crash with exchange of firing.

    He said the plane may have come down due to technical fault or drifted into Pakistani territory due to string wind. Enditem