Iran's opposition leader and defeated presidential candidate Mirhossein Mousavi on Friday urged the government to end its crackdown on opposition protests and release political prisoners.

The Iranian government "should take responsibility for the problems in the country...and release political prisoners," Mousavi said in a statement published on his Kaleme website.

The former prime minister also said that Iran "is in serious crisis" and he is "not afraid to die" for his cause.

"If it is not acknowledged (by the government) that the country is in serious crisis, it would not be possible to resolve the problems," Mousavi said.

"My blood is no redder" than those who "became martyrs for their rightful national and religious demands" during the unrest following the disputed presidential election in June, he said.

Mousavi stressed that high-handed measures against the opposition would harm the country's image and would not solve the problems.

"I clearly and explicitly state that the order to execute, kill or imprison (former parliament speaker and defeated presidential candidate Mehdi) Karroubi, Mousavi and people like us will not solve anything," he said.

Mousavi also insisted that he is not opposed to the Islamic Republic and rejected charges by some hard-liners that he and his supporters were acting as "pawns" of Western countries.

"We are loyal to the constitution," Mousavi said. "We and the Green Movement have an Islamic and national identity and are against the domination of foreigners."

The statement was Mousavi's first one since deadly clashes between security forces and opposition protesters on Sunday, in which at least eight people were killed and hundreds of people were arrested.

Iranian police said they were not involved in the killings and the incidents were under investigation.

Protests gripped Tehran and other Iranian cities after the June 12 presidential election, amid claims that the vote had been rigged in favor of incumbent President Mahmoud Ahmadinejad. Thousands of people were arrested by the authorities, but most of them were released later.

The wide-spread protests in Tehran and other Iranian cities after the June 12 presidential election have become sporadic, but some opposition supporters still take to the streets on some important occasions.