TEHRAN, July 4 -- Mir Hossein Mousavi, the leading opposition candidate in last month's disputed election, released documents Saturday detailing a campaign of alleged fraud by supporters of President Mahmoud Ahmadinejad that assured his reelection, while an adviser to Iran's supreme leader accused Mousavi of treason.

Hossein Shariatmadari, a special adviser to Ayatollah Ali Khamenei, accused Mousavi of being a "foreign agent" working for the United States and a member of a "fifth column" determined to topple Iran's Islamic system of governance. The accusation of treason was the highest and most direct issued by an Iranian official since the June 12 election.

Many in Iran say that government forces are laying the groundwork for arresting Mousavi, who has not been seen in public in more than a week.

In a 24-page document posted on his Web site, Mousavi's special committee studying election fraud accused influential Ahmadinejad supporters of handing out cash bonuses and food, increasing wages, printing millions of extra ballots and other acts in the run-up to the vote.

The committee, whose members were appointed by Mousavi, said the state did everything in its power to get Ahmadinejad reelected, including using military forces and government planes to support his campaign.

The disputed election led to massive demonstrations in the streets of Tehran as the opposition demanded that the results be annulled. An ensuing government crackdown on protesters, which resulted in several deaths, was widely condemned abroad.

Last week, the Guardian Council, Iran's top electoral supervisory body, dismissed the fraud allegations, describing the election as "a golden page . . . of Iran's democratic history." On Saturday, Ahmadinejad blamed what he called Western efforts to "divert" Iranian public opinion during the demonstrations.

"They wanted to break our dignity and independence," the ILNA news agency quoted him as saying.

The government had previously denied the allegations and branded Mousavi, who is supported by another challenger, cleric Mehdi Karroubi, a bad loser.

The report released by Mousavi pointed out that the Interior Ministry, which counted the votes, is headed by Sadegh Mahsouli, a longtime friend of Ahmadinejad. The secretary of the Guardian Council, Ayatollah Ahmad Jannati, had publicly supported Ahmadinejad, as had six others on the 12-member council despite a law requiring them to remain impartial, according to the report.

"The law here was completely broken," said Ali Akbar Mohtashamipour, a top Mousavi campaign official. "What these documents prove is that the two entities that organized the elections were biased and in favor of one candidate."

Mousavi and his supporters say that commanders of the Revolutionary Guard Corps played an instrumental role in the election by campaigning for Ahmadinejad. The report pointed to interviews with Guard Corps publications in which commanders allegedly implied that they would not accept victory by any candidate except Ahmadinejad.

In an editorial, Shariatmadari, who is also editor in chief of the state newspaper Kayhan, identified Mousavi's main supporters as the United States, Israel, the European Union, Iranian foreign-based opposition groups and domestic "plunderers."

"That corrupt movement has been implementing a foreign mission in order to encourage unlawful activities, kill innocent people, create a rebellion, plunder public property and weaken the power of the Islamic system," he wrote.

Shariatmadari said Mousavi was trying to cover up his "crimes" after saying Wednesday that he still fully backs Iran's system of governance.

"His aim is to escape from definite punishment for the murder of innocent individuals, inciting riots and rebellions, hiring some thugs and ruffians to attack the lives, property and honor of the people, clear collaboration with foreigners, performing the role of the fifth column inside the country, and scores of other undeniable crimes," Shariatmadari wrote.

He called for an open trial of Mousavi and former president Mohammad Khatami, one of Mousavi's main supporters, saying, "They must be tried in an open court in front of the eyes of the oppressed people who demand that the blood of their loved ones should be avenged."

Meanwhile, resistance to the disputed elections continued among religious figures.

Grand Ayatollah Yusuf Saanei, who has supported politicians close to Mousavi and advocates more freedoms for young people, women and ethnic minorities, said Friday that many Iranians remain unconvinced that Ahmadinejad's victory was legitimate and urged authorities to safeguard rights.

"I remind you that no instruction or command can be a permission or excuse to violate people's rights, and this could be a great sin," he said.