A Bill has been introduced in the US Congress aimed at enforcing punitive action against companies doing business with Iran that may impact Indo-US nuclear pact and create obstacles for Iran-Pakistan-India gas pipeline.

Chairperson of the US House Foreign Affairs Committee Tom Lantos introduced the Iran Counter Proliferation Act of 2007 on Thursday that will plug loopholes on allowing the US administration to waive sanctions and get tough with companies doing business with Iran.

The Iran Counter-Proliferation Act (H.R. 1400) will "exponentially increase economic pressure on Iran and empower our diplomatic efforts by strengthening the Iran Sanctions Act," Lantos said.

"Until now, by shamelessly exploiting its waiver authority and other flexibility in the law, the Executive Branch has never sanctioned any foreign oil company which invested in Iran. Those halcyon days for the oil industry are over," the California Democrat said.

The proposed legislation will also prohibit nuclear cooperation between the US and any country that provides nuclear assistance to Iran.

It will also increase economic pressure on Iran by expanding the types of investment subject to sanctions, severely limiting the export of US items to Iran, ending all imports from Iran, and preventing US subsidiaries of foreign oil companies that invest in Iran's oil sector from receiving US tax benefits for oil and gas exploration.

"Iran's theocracy must understand that it cannot pursue a nuclear weapons programme without jeopardising the political and economic future of the Iranian state," Lantos said in a statement.