The State Department sent a message to Gaza\'s Hamas leaders on Thursday that it would withdraw some $100 million it is spending in Gaza on health care, agriculture and water infrastructure if they did not back off a demand to audit the books of American-financed charities operating there. The threat, delivered via an intermediary, came after Hamas officials suspended the operation of the \"International Medical Corps\" on Sunday for its refusal to submit to a Hamas audit at the charity\'s site. Tensions have been simmering for months over Hamas\'s relations with the nongovernmental organisations of a number of countries operating in Gaza as the authorities have sought to increase surveillance of the groups. Early this year, Hamas asked all such groups to register with the central government, pay a fee and submit financial reports.