"Colin and Livia Firth have separated. They maintain a close friendship and remain united in their love for their children," a joint statement from their publicists said.
"They kindly ask for privacy. There will be no further comment," it added.
The couple have two sons, Luca and Matteo.
Colin Firth, 59, is best known for playing famously aloof and reserved characters in movies including "Bridget Jones' Diary," "Pride and Prejudice," "Love Actually" and "The King's Speech."
The winner of an Academy Award, Golden Globe and Bafta Award, Firth also has a son with his former partner Meg Tilly.
Livia Firth, 50, is an environmental activist and the co-founder and creative director of Eco-Age, a sustainability consultancy firm. She is also a founding member of The Circle, a women's advocacy group affiliated with singer Annie Lennox, and a UN Leader of Change.
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