The US House of Representatives passed tougher sanctions on Iran, including punishing oil firms and financial institutions that do business with its government, DPA reported.
The House voted 408-8 Thursday in favour of the measure after an earlier 99-1 Senate vote, media reports said. The bill must now be signed by President Barack Obama before becoming law.
The vote followed the UN Security Council's passage this month of its fourth sanctions resolution against Iran over a dispute over its nuclear programme, which its critics fear it is using to develop nuclear weapons but which Tehran said is for civilian purposes only.
The expanded US sanctions focus on depriving Iran of fuel and other refined petroleum products.
Despite having its own crude-oil supplies, Iran has limited refining capabilities so it is unable to meet domestic fuel demand.
The Obama administration, which supports the sanctions, also was seeking to suppress financial transactions by foreign institutions with Iran's powerful Revolutionary Guard, a branch of the country's military that also has oversight of its nuclear programme and controls a business empire.