A top US financial watchdog outlined fresh measures to isolate Iran Tuesday, as Washington attempts to ramp up pressure on the Islamic Republic over its nuclear program.

Securities and Exchange Commission chairman Mary Schapiro told Congress she was working on measures that would make it easier for companies to abandon their stake in firms that trade with Iran.

The rules would "make it clear that an investment company cannot be sued for divesting itself from stocks of companies that deal with Iran," said Schapiro.

It would also make it clearer when companies face sanctions for dealing with Iran.

"There are punitive sanctions that can be levied against companies that violate the Iran sanctions Act," Schapiro told the congressional committee.

"That can create material contingent liabilities that need to be disclosed by public companies."

Earlier this month President Barack Obama signed into law the toughest ever US sanctions on Iran, which he said would strike at Tehran's capacity to finance its nuclear program and deepen its isolation.

The measures, on top of new UN Security Council and European sanctions, aim to choke off Iran's access to imports of refined petroleum products like gasoline and jet fuel and curb its access to the international banking system.

The US and allies accuse Iran of building a nuclear weapon. Tehran denies the charges.

earlier related report
Ashton tells Mottaki in Kabul ready for nuclear talks: ISNA
Tehran (AFP) July 20, 2010 - EU foreign affairs chief Catherine Ashton met Iranian Foreign Minister Manouchehr Mottaki in Kabul on Tuesday and expressed her readiness to hold talks with Tehran over its nuclear programme, ISNA news agency reported.

The two met on the sidelines of an international conference in the Afghan capital attended by representatives of 70 organisations and countries, including US Secretary of State Hillary Clinton.

"The meeting (between Ashton and Mottaki) was organised after Ashton asked for it," ISNA said, quoting its Kabul reporter.

Ashton told Mottaki that she "was ready to start nuclear negotiations and that we are in contact with the Islamic republic and we are serious to find a solution acceptable for both the parties," ISNA reported.

Ashton represents the six world powers -- Britain, China, France, Russia, Germany and the United States -- for holding a dialogue with Iran over its controversial nuclear programme.

During their meeting, Mottaki told Ashton about "Iran's position and its legitimate right concerning the nuclear issue," ISNA said.

Earlier on Tuesday diplomats in Brussels told AFP that the European Union will urge Iran to agree on a firm date for the resumption of nuclear talks when the bloc tightens sanctions against Tehran next week.

EU foreign ministers will approve on Monday "comprehensive and robust" sanctions on trade, financial services, transport and the key energy sectors, according to a draft declaration obtained by AFP ahead of the meeting.

European leaders agreed at a summit last month to impose sanctions targeting the Iranian gas and oil sectors following Tehran's repeated refusal to halt its disputed nuclear activities.

But Brussels has also urged Iran to return to the negotiating table with the six world powers.

Mottaki said last week that talks could begin in September after Ashton reached out to Iran's chief nuclear negotiator Saeed Jalili in a letter in June.

The draft text for the EU foreign ministers' meeting "calls on Iran to seize this opportunity to allay the concerns of the international community about its nuclear programme and agree on a concrete date for talks with the EU High Representative, together with the six countries."

The draft must be approved by EU ambassadors at a meeting on Thursday.

The last high-level talks between Iran and the six world powers were held in Geneva in October 2009.

Western powers have demanded that Iran suspend its uranium enrichment programme, fearing that Tehran would use the material to build a nuclear bomb.

Tehran insists that its atomic programme is a peaceful drive to produce energy.

Iranian President Mahmoud Ahmadinejad announced on June 28 that he was freezing nuclear talks for two months in retaliation for a fourth set of sanctions imposed by the UN Security Council on June 9.

The United States and the European Union later decided to impose their own punitive measures against Iran, targeting the country's key oil and gas sectors.

US President Barack Obama signed the tough US sanctions into law on July 1.