NEW YORK, June 14: The United States is working to press China into codifying into laws its promises made earlier this month to restrict the supply of missile technology to Pakistan, according to a media report here.The permanent five members of the UN Security Council - the US, Britain, Russia, France and China - pledged at their June 4 meeting in Geneva to prevent equipment, materials or technology transfer that can in any way assist programmes in India and Pakistan for nuclear weapons or ballistic missiles capable of delivering such weapons.The American officials agree that the pledge was vague, The New York Times said, adding they were trying to get the Chinese to codify it into their laws and regulations ``in some more enforceable form''.Fearing that the Chinese assistance to Pakistan would continue notwithstanding all the pledges Beijing has made to restrict this technology, the US officials are hoping that the pledge could stretch to include missiles with shorter ranges than thosecovered under the Missile Technology Control Regime (MTCR).The issue is likely to be a key topic on the agenda of United States President Bill Clinton's upcoming talks with his Chinese counterpart Jiang Zemin, the paper said.China, in 1980, had given Pakistan the expertise, nuclear bomb design and fissile material to help it become a nuclear-weapon state and was sanctioned twice by the United States in 1991 and 1993 for providing Islamabad with medium-range missile, M-11, and missile parts in contravention of rules.While China has agreed to abide by the regime which covers missiles that can carry a 500-kg warhead for 300 kms, The Times report says Beijing has so far refused to sign it.Americans are also trying to get Beijing restrict its chemical industry from exporting dual use chemicals and equipment to Iran that could be used for chemical weapons, the paper said.The Chinese are studying US proposals for new and tighter export control methods, The Times added.China denies M-11supplyChina denied delivering M-11 missiles to Pakistan and termed US media reports in this regard as ``entirely groundless''.``The so-called China's proliferation of missiles simply does not exist,'' Chinese foreign ministry spokesman Zhu Bangzao said, ``According to its own non-proliferation policy and recent international commitments, China has adopted a cautious and responsible attitude on the export of military equipment.''Media reports in the US Have quoted American intelligence officials as saying that Chinese-supplied M-11 missiles are now deployed in Pakistan, possibly with nuclear warheads.