Academy Award-winning actress Hilary Swank has said she "deeply regrets" her attendance at a concert and party in Grozny, hosted by Chechnya's Moscow-backed leader Ramzan Kadyrov.
Kadyrov is accused by human rights groups of torture, abductions, and killings.
In a written statement, Swank told The Associated Press that she did not know about the accusations against Kadyrov when she agreed to visit Grozny.
"If I had a full understanding of what this event was apparently intended to be, I would never have gone," Swank said.
During the concert, Swank said she had been impressed by the Chechen government's "passion to make peace and to make something beautiful."
The New York-based Human Rights Watch (HRW) had criticized Swank
-- as well as Belgian action star Jean-Claude Van Damme and British violinist Vanessa-Mae -- for attending a show that "trivializes the suffering of countless victims of human rights abuses."
The AP said representatives for Van Damme and Vanessa-Mae have not responded to requests for comment. HRW has asked the stars to return any money they were paid for attending the concert.
The group has also reportedly sent an inquiry to the British singer Seal, who performed two songs at the concert, which coincided with Kadyrov's 35th birthday.
with agency reports
WATCH: Chechen leader Ramzan Kadyrov hosted an extragavant party on October 5, attended by entertainers Jean-Claude Van Damme, Hilary Swank, and Vanessa-Mae. (Reuters video)