Award-winning Iranian human rights lawyer Nasrin Sotoudeh was briefly detained Wednesday, her husband said, weeks after she was barred from practising for three years.
The couple's car was surrounded by intelligence agents on a highway in Tehran, Reza Khandan wrote on his Facebook page.
"Nasrin and I were arrested. I was freed but Nasrin is still in detention," he said, describing it as "their gift for World Human Rights Day" which was being marked on Wednesday.
Khandan later announced that his wife had been released after a few hours, without giving a reason for what he called her "illegal" detention.
Sotoudeh won the European parliament's prestigious Sakharov rights prize in 2012. She was released last year halfway through a six-year sentence for "actions against national security" and spreading "propaganda against the regime".
In September, a Tehran court barred her from practising for three years.
A message Sotoudeh posted on her husband's Facebook account over the weekend was critical of restrictions on education in Iran, as well as a lack of employment opportunities for political opponents.
Hailing from a religious middle-class family, Sotoudeh, born in 1963, was among the few Iranian lawyers to take high-profile rights and political cases, including juveniles facing the death penalty, before her arrest in 2010.
She has defended journalists and activists including Nobel Peace laureate Shirin Ebadi. When in jail she staged two hunger strikes, in protest at the conditions at Evin Prison in Tehran and at a ban against seeing her son and daughter.
Sotoudeh was released in September 2013 shortly before Iran's then newly elected President Hassan Rouhani, who had campaigned on a pledge to improve civil rights, attended the UN General Assembly.