The portrait is thought to be an aunt of Rembrandt's friend

Now Mr Noortman is offering the picture for sale again with a price tag of �25m.

He said at the time of the purchase that he had bought it for his Maastricht gallery with the intention of making a profit.

The 1632 piece is currently on loan to the National Galleries of Scotland as part of its Rembrandt's Women exhibition.

The exhibition will then travel to the Royal Academy in London, after finishing its run in Scotland on 22 September.

Private sale

Mr Noortman, who is recognised as one of the leading collectors of Dutch and Flemish Old Masters, is offering the picture for sale privately instead of at auction.

He told The Times he is selling it in this way to give potential buyers more time to consider buying the painting, rather than having to make a snap decision at an auction.

The woman portrayed in the Portrait of a Lady is believed to be the aunt of a friend of Rembrandt, a 62-year-old called Aeltje Uylenburgh.

She was the wife of a Calvinist clergyman, Johannes Sylvius, who also had close contact with the painter.

The clergyman vouched for Rembrandt when he got married and Christened the artist's second child, his daughter Cornelia, in 1638.

The previous record for a Rembrandt was Portrait of Bearded Man in a Red Coat which sold for �6m.