NEW YORK (REUTERS) - Imelda Marcos' former secretary was convicted on Monday of conspiring to sell art that the former Philippine first lady acquired during her husband's presidency, including a famous Claude Monet water-lily painting.

After deliberating 2-1/2 hours, a jury in New York state court found Vilma Bautista, 75, guilty of conspiracy and other charges, Manhattan District Attorney Cyrus Vance said in a statement.

She faces 8-1/3 to 25 years in prison, according to a spokesman in Vance's office.

The paintings disappeared around the time her late husband, former Philippine President Ferdinand Marcos, was forced from power in 1986.

Bautista, who lived in New York, was charged last year with secretly keeping and selling Le Bassin Aux Nympheas, one of Monet's Water Lilies series, to a London gallery in 2010 for $32 million (S$39.9 million), according to Vance's office.

She was also accused of secretly keeping Monet's L'Eglise Et La Seine A Vetheuil, Alfred Sisley's Langland Bay and Albert Marquet's Le Cypres De Djenan Sidi Said, with help from her two nephews.

Bautista was guilty of attempting to sell art that "she had possessed secretly for decades and knew to be stolen, and for selling a looted museum-quality painting for her personal enrichment," Mr Vance said.

Bautista, as a member of the Philippine foreign service, acted as Mrs Marcos' unofficial New York-based personal secretary while assigned to the Philippine mission to the United Nations from the early 1970s through 1986, prosecutors said.

During her husband's rule, Imelda Marcos amassed art and other valuables with state assets, according to prosecutors. She was not charged in the case.

The Philippine government charged her and her husband with corruption in 1987, seeking billions in damages for plundering the nation's wealth.

Fran Hoffinger, Bautista's lawyer, did not immediately return requests seeking comment.