Edited sentence: " Washington accuses Iran of seeking to build nuclear weapons, a charge Tehran denies.Andrews, a Democrat, who set up a congressional working group on Iran's nuclear programs two years ago.Kirk, a Republican, and Robert E.The Iran Sanctions Enhancement Act of 2007, introduced by Representative Mark Kirk, Republican-Illinois, and Representative Rob Andrews, Democrat-New Jersey, would threaten sanctions against any company or individual that provides Iran with refined petroleum products or engages in an activity that could contribute to the enhancement of Iran's ability to import refined products after December 31.The United States, which is leading efforts to isolate Iran over its nuclear plans, has said Iran's gasoline imports are a point of "leverage.The bill could potentially lead to sanctions against gasoline brokers, tankers and insurers.The leaders of a bipartisan panel in the US House of Representatives proposed legislation in June 2007 designed to reduce Iran's import of gasoline.The main figures behind the plan were Mark S.US companies are prohibited.from trade with Iran under unilateral sanctions, but most foreign companies are free to trade with Tehran