Islamabad: Finding ‘serious flaws’ in the bills submitted by Pakistan, the US has held up the reimbursement of USD four billion spent by this country's army on the war on terror, a report said on Saturday.

Pakistani Army had submitted bills worth USD 12 billion for reimbursement under the Coalition Support Fund and the US has paid only USD eight billion, officials of Pakistan's Defence Ministry told a meeting of the Parliamentary Standing Committee on Defence.

The officials confirmed that the US Treasury Department had not reimbursed claims for USD four billion. They did not tell the parliamentarians the reasons for this development.

Defence Secretary Lt Gen (retd) Athar Ali too confirmed that the amount had not been paid during a briefing to members of the National Assembly's Standing Committee on Defence presided over by Azra Fazal Pechuho.

The payment was blocked after US treasury officials questioned the genuineness of bills submitted by Pakistan and refused to clear the dues until the objections were addressed to their satisfaction, a daily quoted an official source as saying.

The Defence Secretary told the Parliamentary Committee that as part of an agreement between the two countries, the US had agreed to reimburse costs incurred by the army within Pakistan's borders.

However, Ali chose not to speak about why the amount was not repaid by the US and the objections were raised by the Americans.