CAIRO - Iranian authorities are spreading fear by arresting prominent human rights lawyers to prevent them from representing protesters detained in the aftermath of the country's disputed presidential election, a leading international rights group said.

Human Rights Watch detailed several cases of arrests of lawyers in Iran and said others have been threatened and told not to talk to media -- especially foreign outlets.

The New York-based group released the statement on the clampdown Sunday, a day after global protests backed by HRW and Amnesty International that urged Iran to end the crackdown on opposition activists and release those detained.

Joe Stork, deputy chief of HRW Mideast section, said Tehran seeks to "create an atmosphere of fear among all lawyers who agree to defend political prisoners."

"Many reform supporters arrested after the presidential elections have been denied access to their lawyers, and now they're finding the lawyers imprisoned with them," Stork said in the statement.

Since the June 12 vote, hundreds of thousands of Iranians have held protests denouncing the election as fraudulent until security forces launched a heavy crackdown, arresting hundreds and killing at least 20, according to police. Rights groups believe the number could be far greater.

Protests have also been held world over in sympathy with the Iranian pro-opposition supporters, and Saturday saw rallies in 80 cities, including in the United States. The protesters demanded Iran release hundreds, or even thousands, of people detained during protests denouncing Mahmoud Ahmadinejad's return to power.

HRW said plainclothes officers snatched lawyer Shadi Sadr on July 15 as she was walking to Friday prayers. A friend of the lawyer who was with her at the time is quoted as describing how a car pulling over next to them. Three persons from the car grabbed Sadr, one even beat her with a cable, then threw her inside the vehicle and sped away, HRW said.

At least four other Iranian human rights defenders -- Mohammad Ali Dadkhah, Abdolfattah Soltani, Mohammad Mosatafaie, and Kambiz Noroozi -- have been arrested, according to HRW. Mostafaie was later released but the others remain in custody.

HRW also said families of two detainees told the group their sons don't want lawyers to represent them. One father quoted his son as saying that lawyers "cannot help us" now.

The group also said several other Iranian lawyers have received threatening phone calls or been interrogated, including three members of the Iranian rights group led by Nobel Laureate Shirin Ebadi, which authorities have repeatedly threatened to close down.

According to HRW, one lawyer said he got a call from the intelligence ministry about political prisoners he is representing, and was warned that "talking to media, particularly foreign media, is perceived as cooperating with the enemies."

The post-election turmoil continues to send shockwaves across Iran.

Opposition leader Mir Hossein Mousavi and fellow pro-reform presidential candidate, Mahdi Karroubi, have asked authorities for permission to hold a memorial service on Thursday for victims of the post-election unrest, including a young woman whose death was caught on video and became a symbol for protesters.