Mir-Hossein Mousavi, 67, was foreign minister at the start of the Iran-Iraq war in 1980 and was later appointed prime minister. He was also an advisor to former President Mohammad Khatami, a moderate. Many see him as a pragmatist and a capable administrator. For this reason he might be get the votes of Iranians fed up with the country’s economic crisis. Although a moderate by today’s Iranian standards, he is still a staunch defender of Iran’s Islamist regime and is reputed to be anti-US.

Mehdi Karroubi, 73, was a speaker of the Majlis (parliament) from 1990 to1992 and then from 2000 to 2004 during the presidency of moderate Khatami. Both Karroubi and his party, Etemad Melli, have in the recent years distanced themselves from the radical reformist wings which they accuse of drifting away from the Islamic system that has ruled the country since the 1979 revolution towards a secular course. But he is a proponent of a better understanding with the Western world, especially on issues such as nuclear projects and the Middle East conflict. Karroubi has several times also criticized Ahmadinejad's anti-Israeli tirades and his questioning of the Holocaust, saying that raising such irrelevant issues has only harmed Iran's international image

Mohsen Rezaee, 55, is former Pasdaran (Guardians of the Revolution) commander and in 1997 worked under former President Hashemi Rafsanjani. He is seen as a conservative and was accused by Argentina of involvement in the 1994 bombing of a Jewish cultural centre in Buenos Aires.

At first glance none of the candidates appear to pose a real threat to Ahmadinejad.

For many Iranians choosing one of the four is not much of a choice since there is not much difference between them. A low turnout is expected on 12 June.

The field of candidates was restricted to four out of a total of 475 applicants, including Khatami who was president from 1997 to 2005 and bowed out.

About 46.2 million Iranians are eligible to vote; at least half of them young voters, many of whom are either uninterested in politics or disaffected.

Conversely, the international community is more interested though, closely monitoring any possible signs of détente that might be coming out of Iran.

Tehran’s nuclear programme remains a major bone of contention because despite its officially peaceful nature it could conceal a military component.

And world opinion, especially in Israel, is very much concerned about it, something which was not allayed yesterday when Iran test-fired a rocket with a 2.500 kilometre range capable of striking Israel and US Navy ships in the Persian Gulf.