Geneva, Switzerland (CNN) -- An Iranian Nobel laureate led a small demonstration in front of the United Nations office in Geneva on Monday, protesting the continued imprisonment of human rights activist and fellow lawyer Nasrin Sotoudeh.
"We are worried about her. That is why we are here," said Shirin Ebadi, a human rights lawyer who won the Nobel Peace Prize in 2003. "We are worried for her life. It is very dangerous, and she is in a critical situation."
Sotoudeh was arrested in Iran on September 4 and has been reportedly imprisoned in solitary confinement, embarking on a hunger strike in an effort to pressure authorities to release her, according to a statement from Reporters Without Borders. She has been held more than 100 days, the statement said.
Ebadi left Iran just before that country's controversial 2009 elections returned President Mahmoud Ahmadinejad to power. Since then, her sister, other relatives and some of her associates have been jailed or harassed by Iranian authorities, she has said.
Sotoudeh was the attorney for Arash Rahmanipour, one of two men executed by the Islamic republic in early 2010 after being charged with being an enemy of God and belonging to a banned opposition group. She said her client's family had been scheduled to visit him in prison the same day and learned of his execution on television.
One report in Iranian media linked Rahmanipour's arrest to the protests that followed the 2009 election, but Sotoudeh disputed that report.
"Both of these men were arrested two months before the elections and they were in prison until their sentences were carried out," she said in January. "So how can someone who's in prison take part in protests?"
Monday's protesters carried placards and held photos of Sotoudeh in an effort to focus international attention on Sotoudeh's continued imprisonment.
CNN's Fred Pleitgen contributed to this report