The US Congress approved punishing new sanctions targeting Iran's energy and shipbuilding sectors, a day after President Barack Obama unveiled measures to cripple Tehran's nuclear drive.
The House of Representatives voted overwhelmingly 421-6 for the measure, which Foreign Affairs Committee chair Ileana Ros-Lehtinen described as the toughest sanctions yet imposed on the Islamic republic over its refusal to rein in its nuclear programme.
The new rules — which target any person or company which works with Iran's petroleum or natural gas sector, provides insurance to the National Iranian Oil Company, engages with uranium mining with Iran, or sells oil tankers to the country — passed the Senate by a unanimous consent vote.
"This bipartisan, bicameral agreement seeks to tighten the chokehold on the regime beyond anything that has been done before," Ros-Lehtinen told the House.
She said the sanctions effectively put Iran's energy sector "off limits, and it blacklists any related unauthorized dealings," ultimately "depriving Iran of hard currency and funds needed to sustain its nuclear programme".
The legislation, which goes to Obama for his signature, is a reconciliation of a bill passed by the House in December and one passed by the Senate in May. Lawmakers wanted to move on the bill before going into their August recess.
It beefs up sanctions passed by Congress last year which imposed penalties on foreign financial institutions that do business with the Central Bank of Iran or other Iranian finance firms, essentially barring Iran's business partners from the lucrative US market.
The House's number two Democrat, Steny Hoyer, said the bill would deny Iran 80 percent of its hard-currency earnings.
"As long as Iran continues to pursue nuclear weapons, call for the destruction of Israel, and provide arms to terror groups like Hamas and Hezbollah, it will face the consequences in the form of sanctions, isolation and the continuing reality of the option of military action," he said.
White House policy is "prevention, not containment," and Obama "is keeping all options on the table," Hoyer said.
The debate about sanctions comes amid deliberation over a possible first strike against Iran's nuclear facilities by Israel. Iran has insisted its nuclear programme is for peaceful purposes.
Last weekend, Israeli Prime Minister Benjamin Netanyahu expressed his doubts about the effectiveness of sanctions on Iran, saying that "all the sanctions and diplomacy so far have not set back the Iranian programme by one iota".
Republican White House hopeful Mitt Romney entered the fray last weekend, when he met with Netanyahu in Israel and said a nuclear Iran was "unacceptable" and that he would back Israel's right to defend itself.
In the wake of Netanyahu's remarks, and amid stalled negotiations with Iran, Obama on Tuesday tightened sanctions, targeting Iran's oil export sector and a pair of Chinese and Iraqi banks accused of doing business with the country.
The American Israel Public Affairs Committee, one of the most powerful lobbies in Washington, applauded the bill, calling it "the strongest set of sanctions the United States has ever imposed on any country during peacetime".
"The implementation of this bill would subject virtually all of Iran's energy, financial, and transportation sectors to US sanctions," AIPAC said in a statement.