Iran will respond on Friday to incentives offered by six world powers to try to entice Tehran to stop enriching uranium, which they fear could result in a nuclear bomb.
European Union states agreed on June 23 to impose new sanctions on Iran, including an asset freeze on its biggest bank, over its refusal to meet demands to curb its nuclear programme.
Following are some details about the sanctions and those already imposed by the U.N. Security Council and the United States.
* WHAT DO THE NEW EU SANCTIONS INCLUDE?
-- The new sanctions will target businesses and individuals that the West alleges are linked to Iranian nuclear and ballistic programmes.
-- There are visa bans on senior officials such as Revolutionary Guards head Mohammad Ali Jafari, Defence Minister Mostafa Mohammad Najjar and atomic energy chief Gholamreza Aghazadeh.
-- Iran's biggest bank, Bank Melli will face an asset freeze under the moves, while visa bans will target "very senior experts" inside Iran's nuclear and ballistic programmes.
* WHAT SANCTIONS HAVE ALREADY BEEN IMPOSED?
-- The U.N. Security Council imposed three sets of sanctions on Iran, in December 2006, March 2007 and March 2008.
-- The first round covered sensitive nuclear materials and froze the assets of Iranian individuals and companies associated with the programme. It gave Iran 60 days to suspend uranium enrichment, a process which can be used to make nuclear power plant fuel or bomb material. Iran did not stop.
-- The second round included new arms and financial sanctions. It extended an asset freeze to 28 additional groups, companies and individuals engaged in or supporting sensitive nuclear activities or development of ballistic missiles.
-- State-run Bank Sepah and commanders and firms controlled by Iran's Revolutionary Guards, including commanders of one of its units, the Qods Force, were included on the list.
-- The resolution invoked Chapter 7, Article 41 of the U.N. Charter, which makes most of its provisions mandatory but excludes military action. Iran again failed to meet a 60-day deadline to halt enrichment.
-- On March 3, 2008, the U.N. Security Council imposed the third round of sanctions for refusing to suspend sensitive nuclear activities. Tehran dismissed the council's decision as illegal and illegitimate.
-- The sanctions resolution called for more travel and financial curbs on Iranian individuals and companies and makes some restrictions mandatory.
-- It also expanded a previous partial ban on trade in items with both civilian and military uses to cover sales of all such technology to Iran.
-- The new resolution added the names of 13 individuals and 12 companies to the list of people and firms suspected of aiding Iran's nuclear and missile programmes.
-- Tehran has so far ignored all council and IAEA resolutions demanding it freeze its uranium enrichment programme.
* U.S. SANCTIONS:
-- The United States has imposed various sanctions on Iran since 1979 after radical Iranian students stormed the U.S. embassy in Tehran and took U.S. diplomats hostage.
-- The measures prohibit most trade between the United States and the Islamic Republic.
-- In 1995, then President Bill Clinton issued executive orders preventing U.S. companies investing in Iranian oil and gas and trading with Iran. However Tehran has found plenty of other willing customers outside of the United States.
-- The same year, U.S. Congress passed the Iran-Libya Sanctions Act (ILSA) -- from which Libya was later dropped -- requiring the U.S. government to impose sanctions on foreign firms investing more than $20 million a year in Iran's energy sector. It was extended for five years in September 2006. No foreign firms have been penalised.
-- In October 2007 the U.S. slapped sanctions on Bank Melli, Bank Mellat and Bank Saderat and also branded the Revolutionary Guards a proliferator of weapons of mass destruction. Washington also imposed sanctions on firms controlled by the Guards and on the Qods Force, saying the unit backed terrorists.
-- In January 2008, the United States imposed sanctions on Brigadier-General Ahmed Foruzandeh from the Qods force for fomenting violence in Iraq.
-- Last week a U.S. Senate panel approved legislation to strengthen U.S. sanctions on Iran. The measure would tighten the trade ban on goods to and from Iran. The bill also would expand financial sanctions on some individuals, and penalize U.S. companies if their foreign subsidiaries do business with Iran.