Iran re-arrests leading human rights lawyer Nasrin Sotoudeh

"While returning from the sit-in outside the Bar Association in Tehran, Nasrin was detained along with several friends and colleagues," her husband, Reza Khandan, said on his Facebook page.

"They photographed and ran identity checks on all the detainees and then released everyone but Nasrin, who is still detained wantonly and without a court order."

Sotoudeh, who has represented Iranian opposition activists, was sentenced to six years in jail in 2010 and banned from practice after being convicted of spreading propaganda and conspiring to harm state security.

Her case came to international attention in 2012 when she embarked on a 50-day hunger strike against a travel ban on her daughter.

The United States and human rights campaigners like Amnesty International criticized the Islamic Republic over the case and Sotoudeh was freed in September 2013 ahead of a visit to the United Nations by President Hassan Rouhani, soon after he swept to election victory in part on promises of liberal reforms.

Speaking to Reuters by telephone on Wednesday, Sotoudeh said she was protesting outside the Iranian Bar Association to demand a reversal of a three-year ban on her practicing law.

Iran's Bar Association, under pressure from conservative hardliners who dominate the judiciary, this month banned her from practice, enforcing that part of her 2010 sentence.

"From the first day in prison, my interrogator vowed to use all his powers to stop me from practicing law," she had said on the second day of her protest. "Four years on, he seems to have succeeded with the help of others."

She said on Wednesday she would stop protesting once the right of dissidents to work and the bar's independence were restored. She had been accompanied in her protest by 15 other people, including human and women's rights activists.

"For years Iranian dissidents have been denied the right to live, work and seek education," she said on her husband's Facebook page last week, referring to a crackdown on pro-democracy activists since 2009.