The bill, which has the support of 23 senators from both major US parties, would empower President Barack Obama to punish petroleum exporters supplying Iran, including a ban on doing business in the United States, they said.

Democratic Senator Evan Bayh, Republican Senator Jon Kyl and independent Senator Joseph Lieberman are the lead authors of the measure, which comes one week after lawmakers introduced a similar bill in the House of Representatives.

The senators were to unveil the legislation at a press conference on Tuesday.

"Limiting Iran's access to essential energy supplies could aid US diplomatic efforts to achieve concessions from the Iranian government regarding its nuclear operations," Bayh, Kyl and Lieberman said in a joint statement.

At the same time, a key committee in the House will take up that chamber's version of the legislation, which comes as US lawmakers express growing frustration at the pace of diplomatic progress in nuclear talks with Iran.

Iran, though rich in oil, is estimated to rely on gasoline imports to meet 40 percent of domestic demand, most of it coming from five European firms and one Indian company.

Entities potentially affected include the Swiss firm Vitol, the Swiss/Dutch firm Trafigura, the French firm Total, the Swiss firm Glencore, and British Petroleum, as well as the Indian firm Reliance, while Lloyds of London insures the majority of tankers carrying gasoline to Iran.

The new legislation would expand the criteria under which a company could face US sanctions under a 1996 law targeting investments over more than 20 million dollars in Iran's oil and gas infrastructure.

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