TEHR AN (AFP) - The race for Irans presidency hotted up on Saturday as the two key moderate challengers to incumbent Mahmoud Ahmadinejad formally registered to stand against him in the June election. Mir Hossein Mousavi, a former prime minister who steered Irans economy during the brutal war with Saddam Hussein in the 1980s, has the support of reformist former president Mohammad Khatami. They join the former head of Irans Revolutionary Guards Corp, Mohsen Rezai, who like Ahmadinejad registered his candidacy on Friday. The conditions today are not the best or what the Iranian people deserve, Mousavi said after submitting his bid to the interior ministry. I have come to defend the freedom of thought and expression, to pursue constructive interaction and better ties between Iran and the world, he said as dozens of his supporters shouted slogans backing his candidacy. Mousavi, who describes himself as a reformist who refers to the principles of the 1979 Islamic revolution, has promised to change Irans extremist image around the world but also to pursue its controversial nuclear programme. Mousavi was Irans last prime minister as the post was abolished in 1989. With his bid for the presidency, he is seeking a comeback after two decades in the political wilderness. As he registered his candidacy, Karroubi, a veteran reformist who is now 72, called on the Iranian authorities to respect the verdict of the people. He said the June 12 election was a crucial test for both the Ahmadinejad government and the powerful Guardians Council, the body, which vets all candidates for election. The Guardians Council, especially its influential members... despite their rhetoric supporting this government, must be very careful in guarding the peoples vote, he said. Describing the Ahmadinejad government as incapable and unfit to run the country, Karroubi said he was standing for change. Karroubi contested the last presidential election in 2005 but lost to Ahmadinejad. On Saturday, he demanded that the Revolutionary Guards not interfere in this years election. We want a free election without the interference of armed forces. We are ready to be defeated or be triumphant, but that should be according to the peoples mandate, he said. Ahmadinejad has said he is hopeful of winning. But he insisted he would not allow anybody to be aggressive towards other candidates in my name during the campaign. In his four years as president, Ahmadinejad has drawn condemnation abroad for his anti-Israel tirades and for doggedly pursuing Irans nuclear programme which global powers suspect is cover for a drive for the bomb. At home, he has been accused of stoking inflation through expansionary economic policies that critics say have failed to reduce unemployment or poverty. Whoever wins the June election will take over the presidency at a key time when the new US administration of President Barack Obama has been making overtures to Iran. Although major foreign policy issues remain the preserve of the supreme leader Khamenei, the outcome could influence the success of any rapprochement between Tehran and Washington, which have had no diplomatic relations since the aftermath of the 1979 revolution. Amin Sabooni, execution editor of the state-owned English language newspaper Iran Daily said that with just over a month to go till polling day, it was still a bit soon to predict the outcome as things here change abruptly. It is still not clear to me what the candidates have to offer, especially on how to fix the economy and handle relations with the United States. The four main candidates were just a few among the array of hopefuls to throw their hats into the ring before the end of the five-day registration period later on Saturday. With less than 12 hours to go until the midnight (1930 GMT) deadline, election committee chief Kamran Daneshjoo told state television at least 250 had registered. But the vast majority are expected to be disqualified by the Guradians Council. In 2005, just seven candidates out of more than 1,000 hopefuls were approved.