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Mia Farrow has ended her hunger strike after 12 days.

Farrow, 64, had been subsisting on a liquid diet since April 27 to raise more awareness for the Darfur humanitarian crisis.

"I have been instructed by my doctor to stop my fast immediately due to health concerns -- including possible seizures," she tells Entertainment Tonight. "I am fortunate. The women, children, and men I am fasting for do not have this option."

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"When I began this fast twelve days ago," Farrow continues, "I hoped another would take my place, and another, and another, until the expelled humanitarian agencies are readmitted and finally there can be justice and peace for the people of Darfur. Richard Branson has stepped forward and so I have ended this fast."

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Branson -- the 58-year-old British founder of Virgin Atlantic Airwaysand the Virgin record label and music store chain -- said he is "honored" to be taking over the fast for the next three days.

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"Over a year-and-a-half ago, I traveled to Darfur and was horrified by the stories that people of all ages shared with us," he said. "Now, with 13 aid organizations expelled from the country, over one million people are at grave risk. We cannot stand and watch as one million people suffer. We all need to stand up and demand that international aid is restored and that the people of Darfur are protected and given the chance to live in peace."