The "Rosemary’s Baby" star wants to help Suleiman Jamous, a leader of the Sudanese Liberation Army who needs a stomach biopsy, but has been confined to a U.N. base in Kadugli, near the war-torn Sudanese region of Darfur, for more than a year, the New York Daily News reported Tuesday.
The Khartoum government has warned Jamous he would be arrested if he leaves the base, but insisted it was open to talks on his release.
"I am therefore offering ... to exchange my freedom for his," Farrow wrote in a letter to Sudan President Omar Hassan al-Bashir. "(I know) he will apply his energies toward creating the just and lasting peace."
The 62-year-old goodwill ambassador for UNICEF and mother of 14 biological and adopted children has visited Darfur twice.
She was traveling in Africa and couldn't be reached for comment on her unusual proposal.
There was no immediate response from the Sudan.