US lawmakers on Wednesday will introduce a bill that would tighten sanctions on Iran, as Tehran held key talks with world powers over its contested nuclear drive which it described as a "milestone."
The bipartisan House legislation, a copy of which was obtained by AFP, would allow President Barack Obama to impose penalties on foreign entities that provide Iran with goods that help maintain its struggling economy.
It also would provide Obama with broader authority to target strategic imports, such as mining or power generating equipment, that could help Iran with its nuclear program, which the West and Israel say is a front for weapons development.
The bill would also designate the Iranian Revolutionary Guard Corps as a foreign terrorist organization.
Such designations of administration policy are made through the US State Department, so it was not immediately clear how the House designation would affect US ties with Iran.
Similar language was inserted into Senate legislation in 2007, but the bill never became law.
Iran is already under the toughest sanctions regime, including four separate UN resolutions, ever devised. The measures are aimed at forcing the country to rein in its nuclear program, which Tehran insists is purely peaceful.
The sanctions are biting hard, slashing oil revenue and pushing the country close to recession as it seeks ways such as bartering to stay afloat, a US Government Accountability Office report said Tuesday.
News of the proposed bill comes just as Iran concluded a key meeting in Kazakhstan with the P5+1 powers -- the United States, China, Russia, Britain, France and Germany -- aimed at easing the nuclear standoff.
A revised P5+1 offer put on the table reportedly involves easing sanctions on Iran's gold and precious metals trade while simultaneously lifting some restrictions on the Islamic republic's banking operations.
But they still want Iran to halt enriching uranium to 20 percent, which for the international community is the most worrisome part of Iran's activities.
"Things are taking a turning point and I think the Almaty meeting will be (seen as) a milestone," Iran's Foreign Minister Ali Akbar Salehi said in Vienna. The two sides agreed to hold new talks in March and April.