LOS ANGELES (Reuters) - Lawyers for Brad Pitt on Thursday threatened legal action against anyone publishing recent photographs they say were taken by paparazzi of the actor and his newly enlarged family at their French estate.

Pictures of Pitt and his family in France were "surreptitiously" snapped using a powerful telephoto lens and sold to an unidentified buyer, the Los Angeles lawyers said in a letter published by the U.S. Web site The Smoking Gun (http://www.thesmokinggun.com).

The lawyers did not say which family members were in the pictures.

Pitt and actress Angelina Jolie, the mother of his children, have reportedly sold exclusive picture rights to the first photographs of their newborn twins to a U.S. publication for $11 million. The money would go to charity.

The legal warning came a week after Jolie left the hospital in Nice with twins Vivienne Marcheline and Knox Leon, who were born on July 12. The family has rented a villa in nearby Provence.

Pitt's lawyer, Yael Holtkamp, said the taking of the photos was a "malicious violation" of the actor's privacy rights under both French and California law.

Holtkamp said one unspecified photo agency that had already sold the pictures had agreed to stop further sales and removed them from its Web site.

Several celebrity Web sites that had links to the pictures had removed them by late on Thursday.

The Smoking Gun, which publishes legal documents and arrest warrants of celebrities, published the letter sent to it by Pitt's lawyers, who also threatened legal action against the Web site should it post the photos. Smoking Gun said it had never purchased a paparazzi photo in its 11-year history.

Jolie, 33, and Pitt, 44, have four other children -- Maddox, Pax, Zahara and Shiloh -- three of whom are adopted.

(Editing by Steve Gorman and Peter Cooney)