WASHINGTON — One of Iran’s leading dissidents is calling on the U.N. secretary-general, Ban Kimoon, to condemn what he describes as “deplorable conditions” for his fellow dissidents.

Akbar Ganji’s open letter, signed by more than 300 public intellectuals, including Noam Chomsky and Howard Zinn, comes as the Iranian president is preparing to address a forum at Columbia University today. In the letter, Mr. Ganji also takes a clear aim at President Bush for keeping military options on the table and not doing enough to support a two-state solution for Israel and the Palestinian Authority.

Iran is the main issue for Americans, at least, at this week’s U.N. General Assembly.

Last night, CBS ran an interview with President Ahmadinejad, in which he said his nation was not seeking nuclear weapons, a claim that runs counter to the Iranians’ continuing insistence on enriching uranium, despite prior agreements to suspend such activities. Also yesterday, the military adviser to Iran’s supreme leader, Ayatollah Ali Khamenei, warned, “Today, the United States must know that their 200,000 soldiers in Iraq and Afghanistan are within the reach of Iran’s fire.”

Last week, word leaked out that Mr. Ahmadinejad, whose country hosts senior Al Qaeda leaders and whom the American military recently accused of supporting the Taliban in Afghanistan, intended to visit ground zero and lay a wreath. While Mr. Ahmadinejad has rescinded his request to travel to the site, he will address an audience today at Columbia and the National Press Club via teleconference.

Mr. Ganji has been exiled from Iran since 2006, when he left for Russia to receive the first of many journalism and human rights prizes. He was first sent to prison in 2000, ostensibly for attending a state-sanctioned conference on Iranian reform in Germany and publishing articles and a book in Persian blaming leading regime figures for authorizing a chain of murders of intellectuals in the 1990s.

Nonetheless, since arriving in North America, Mr. Ganji has been particularly critical of the Bush administration. In his open letter, he writes: “The Bush Administration, for its part, by approving a fund for democracy assistance in Iran, which has in fact been largely spent on official institutions and media affiliated with the US government, has made it easy for the Iranian regime to describe its opponents as mercenaries of the US and to crush them with impunity.”

State Department officials recently told The New York Sun that many Iranians have continued to apply for the money but have declined to give their names because of the crackdown against democracy activists. Mr. Bush was the first world leader to call for the release of Mr. Ganji from Evin Prison in 2005, when he was on a hunger strike that summer.

The rise of Mr. Ahmadinejad appears to be linked to Mr. Ganji. When he was on medical leave from Evin Prison in 2005, Mr. Ganji told the reformist Web site Rooz online that he believed Iranians should boycott the presidential contest Mr. Ahmadinejad allegedly won. At the time, no serious reformers were allowed on the ballot, and three of Mr. Ahmadinejad’s vetted rivals accused the Revolutionary Guard of stealing the election.

Mr. Ganji is even more critical of Iran’s ruling clerics. In his letter, he describes what might be called the “Talibanization” of Iran, a country that is now adopting the Koranic punishment of stoning as legal sanction for a host of moral crimes. He says that recently some female schoolteachers who protested for higher pay have been internally exiled and “workers who ask to be allowed to form unions in order to struggle for their corporate rights are beaten and imprisoned.”

Mr. Ganji asks Mr. Ban if he is aware that in Iran, “writers are lawfully banned from writing,” citing a section of the Iranian penal code that prohibits “propaganda against the ruling system.” At the end of his letter, Mr. Ganji asks Mr. Ban why the U.N. Security Council has criticized his country’s nuclear program but has had nothing to say about Iran’s human rights record.

“The people of Iran are asking themselves whether the UN Security Council is only decisive and effective when it comes to the suspension of the enrichment of uranium, and whether the lives of the Iranian people are unimportant as far as the Security Council is concerned,” he writes. “The people of Iran are entitled to freedom, democracy and human rights.”