TEHRAN , Iran ( CNN ) -- Three leading Iranian reformists who have rejected the results of last month 's election questioned the legitimacy of President Mahmoud Ahmadinejad 's government Wednesday . Mehdi Karrubi is vowing to `` stand by the people and the revolution , until the end of my life . '' This comes as Ahmadinejad is set to take office at the end of the month . Presidential candidate Mehdi Karrubi wrote a letter in his party 's newspaper , saying he would not recognize the government and vowing to `` stand by the people and the revolution , until the end of my life . '' His statement prompted Iran 's government to block publication of the newspaper . Read Karrubi 's letter PDF . Ahmadinejad 's main political rival , Mir Hossein Moussavi , also released a statement Wednesday criticizing the government and its crackdown on the media , which he said has created a `` bitter , coup d'etat atmosphere '' in Iran . `` We will stand firmly in order to preserve this valuable accomplishment [ revolution ] , '' Moussavi said . `` Unless we succeed in this , this government will not have legitimacy . The system and the heritage of the Islamic revolution are the fruits of our 200-year-old struggle against oppression . `` Read Moussavi 's statement PDF . Iran 's former reformist President Mohammad Khatami called on Iranians to keep up the struggle , noting that `` all doors are not yet closed . '' Read Khatami 's letter PDF . `` We must not lose our social capital this easily , '' Khatami told progressive Iranian newspaper Tahlile Rooz . `` I know Moussavi as one of the faithful , original and valuable capitals of our revolution , and considered his return to the political scene as a great chance . '' In a separate posting on his Web site , Khatami accused the government of having restricted communications in the country . `` The state-owned media outlet shows the same scenes over and over again , in order to provoke people 's feelings , '' he said . `` Where was this media outlet when tens of people were killed and hundreds of people beaten ? '' In his statement , Moussavi called for the release of jailed reformists and said he will participate in the creation of a `` legal organization '' that will release proof of fraud in the June 12 presidential election and take its case to the courts . He said the current political issue is a `` family dispute '' and cautioned against asking for outside help , warning , `` We will regret it . '' `` Many '' have asked Moussavi to end his struggle and `` close my eyes , '' but he warned , `` If we do not stand our grounds now , then we will have no guarantees that we wo n't be at this exact point in the future , face to face with the bitter events of this election . '' Karrubi called the actions of the government before and after the controversial June 12 voting `` the foundation for the annulment of the elections , '' according to a copy of his letter on the party newspaper 's Web site . `` I will not recognize the legitimacy of the government which has resulted from this process , '' Karrubi said in the letter . The 72-year-old cleric also said he `` will not participate in any of its processes , in any way '' and said he is `` ready to cooperate with pro-change people and groups . '' Karrubi 's party , Etemed Melli , said Iran 's Ministry of Culture and its attorney general prevented the publication of its newspaper because it carried the letter . He and Moussavi have questioned the legitimacy of the vote count of the presidential election that gave Ahmadinejad an overwhelming victory . That outrage sparked bloody street protests and a clampdown on international media coverage , as well as access to certain Web sites . At least 20 protesters were killed in the chaos and more than 1,000 were detained in Tehran , the head of Iranian internal security forces Brig . Esmaeil Ahmadi said , according to Iranian state-run media reports on Wednesday . The actual death toll may be higher , but restrictions on media have made it difficult to verify . Human Rights Watch on Wednesday called on Iran to release prominent Iranian reformist Saeed Hajjarian , who has been imprisoned since June 15 . He is one of several jailed reformists accused of orchestrating the post-election violence in Iran . Hajjarian , 55 , was severely disabled after he was shot in the head in a 2000 assassination attempt that left him confined to a wheelchair with severe brain and spinal cord injuries . His wife , Vajiheh Marsoussi , is a physician and has visited Hajjarian in Tehran 's Evin prison . She told Human Rights Watch that his medical condition was `` deteriorating severely . '' Meanwhile , questions surrounded an announcement in government-run Iranian media that Ahmadinejad canceled his trip to Libya on Wednesday . The trip , which had not been finalized , was canceled because of the president 's `` huge workload '' at home and `` other priorities , '' Iran 's Foreign Ministry spokesman Hassan Qashqavi said , according to the Iranian Students ' News Agency . Four days after the controversial election , Ahmadinejad went to Russia to meet with leaders there , where he was welcomed as the `` newly re-elected president of Iran '' despite the ongoing street protests . He returned to Iran that same day . Ahmadinejad will be sworn in before parliament Sunday , July 26 , according to Iranian media reports . He will participate in a ceremony officiated by Supreme Leader Ayatollah Ali Khamenei a couple of days later , and then his second term will officially begin .
NEW : Former President Khatami accuses government of restricting communications . Mehdi Karrubi says he will not recognize government . Mir Hossein Moussavi criticizes government 's crackdown .