A rare copy of the Magna Carta, the document that enshrined human rights in English law, is to be sold in New York.

The copy owned by the Perot Foundation is expected to fetch more than $20m (£9.94m), auctioner Sotheby's says.

The copy on sale, dating from 1297, was bought by Ross F Perot in 1984 and is the only one in private ownership.

King John sealed the original Magna Carta in 1215, outlawing imprisonment and the seizure of property without due legal process, including trial by jury.