TEHRAN, Iran — Iran's embattled opposition leaders accused the government of becoming more brutal than the shah's regime in Web statements Saturday, and authorities announced a new Internet crackdown aimed at choking off the reform movement's last real means of keeping its campaign alive.

Two of Iran's top pro-reform figures said police used excessive force against anti-government protesters who took to the streets earlier this month on the sidelines of state-sanctioned rallies to mark the 30th anniversary of the U.S. Embassy takeover.

Mir Hossein Mousavi and Mahdi Karroubi, who led the protest movement rejecting the legitimacy of President Mahmoud Ahmadinejad's June re-election, said authorities wielding batons even struck women on their heads. They called such treatment an ugly act that was not even seen during Shah Mohammad Reza Pahlavi's response to the 1979 Islamic revolution that toppled him.

"I can't understand why they should treat people like this," Karroubi was quoted as saying by several opposition Web sites. "I struggled against the Pahlavi regime for 15 years … but there were no such crackdowns."

Such Web statements have been the mainstay of an opposition movement struggling to stay alive despite being brutally swept off the streets in the weeks after the June 12 election. Mousavi and his supporters contend that he was the rightful winner of the vote, but that Ahmadinejad was fraudulently declared the winner.

In a clear effort to silence the opposition's Internet outlet, Iranian authorities announced they were deploying a special police unit to sweep Web sites for political material and prosecute those deemed to be spreading lies, Iranian media reported Saturday.

Most opposition Web sites are already banned, but activists have continued to set up new sites within days of the old ones being blocked.

The new 12-member police unit will report to the prosecutor's office. Police Col. Mehrdad Omidi, who heads the unit, said it will go after "insults and the spreading of lies," terms widely used by the judiciary to describe opposition activities.

"Authorities know that the Internet is one of the few available channels for the opposition to make its voice heard. They want to silence opposition voices," said reform-minded journalist Akbar Montajabi, who described the measure as the latest set of restrictions imposed on media in the country.