1 December 2011 Last updated at 13:31 ET

Q&A: Iran sanctions

Fresh sanctions have been agreed against Iran at a meeting of EU foreign ministers in Brussels, as international pressure on Iran over its nuclear programme intensifies.

What international sanctions are already in place on Iran?

The UN ratified four rounds of sanctions against Iran between 2006 and 2010 in reaction to its failure to halt uranium enrichment and co-operate with the International Atomic Energy Association (IAEA) over its nuclear programme. These sanctions include a ban on the supply of heavy weaponry and nuclear-related technology to Iran, a block on Iranian arms exports, and an asset freeze on key individuals and companies. Resolution 1929, passed in 2010, mandates cargo inspections to detect and stop Iran's acquisition of illicit materials.

The EU has imposed its own restrictions on trade in equipment which could be used for uranium enrichment and has put in place an asset freeze on a list of individuals and organisations which it believes are helping advance the country's nuclear programme, and has banned the individuals on the list from entering the EU. On 1 December, the EU added 39 people and 141 companies to the list, although it has not yet named them.

Last year the EU also banned the export to Iran of key equipment and technology for the refining and production of natural gas, in an attempt to hit the crucial energy sector of the Iranian economy.

Which countries have imposed bilateral sanctions on Iran?

The US has longstanding comprehensive sanctions in place on Iran. Diplomatic relations between the two countries were broken in April 1980 after the American embassy in Tehran was stormed by students during Iran's Islamic Revolution. Since then the US has imposed successive rounds of sanctions, citing what it says is Iran's support for international terrorism, human rights violations and refusals to co-operate with the IAEA.

The US sanctions prohibit almost all trade with Iran, making some exceptions only for activity "intended to benefit the Iranian people", including the export of medical and agricultural equipment to Iran, sending humanitarian assistance and trade in "informational" materials such as films and publications.

In late November the US, UK and Canada announced more bilateral sanctions to be placed on Iran, in reaction to an IAEA report which suggested Iran's nuclear programme may have a military purpose. The US expanded sanctions to target companies that aid Iran's oil and petrochemical industries, while the UK ordered all British financial institutions to stop doing business with their Iranian counterparts, including the Iranian central bank.

Several other countries including Switzerland, Japan, Australia and Canada have also imposed bilateral sanctions on Iran in recent years in response to Iran's lack of co-operation with the IAEA.

Could further measures be taken?

One step which is thought to be under consideration is placing an embargo on Iranian oil sales, as the EU recently did with regard to Syria. Some members of the US Congress are sponsoring legislation urging President Obama to target Iran's central bank and any foreign institutions that do business with it, potentially reducing the flow of oil revenue to Iran and causing a drop in its oil exports. The US Treasury has expressed its readiness to consider such measures.

This would have a big impact on the Iranian economy, but given Iran's position as a major global oil exporter, an embargo could also have the consequence of driving up the global oil price and harming Western economies, in Europe in particular.

Which countries are opposed to sanctions on Iran?

Russia and China have expressed their opposition to further sanctions on Iran, making more measures at the UN Security Council highly unlikely, as both countries have a veto there.

Russia's Foreign Ministry has criticised the IAEA report that has sparked the latest row and said the imposition of bilateral sanctions is "fraught with the gravest consequences".

China and Russia have been expanding their roles in Iran's economy in recent years - China is currently the largest buyer of Iranian crude oil.