Freud painted Benefits Supervisor Sleeping back in 1995
A painting by Lucian Freud is expected to become the most expensive work by a living artist sold at auction when it goes under the hammer next month.
The 1995 work, Benefits Supervisor Sleeping, is estimated to fetch between $25m and $35m (£12.7m to £17.7m).
The current auction record for a picture by a living artist is Hanging Heart, by Jeff Koons, which sold for $23.6m (£11.3m) in November 2007.
Freud's painting has never been seen in public in the UK before.
It will be shown on 11, 14 and 15 April at Christie's in London before being auctioned in New York.
The life-size work depicts a naked Sue Tilley, a benefits supervisor from London whom Freud first painted in 1993.
Ms Tilley, nicknamed "Big Sue", was introduced to the painter, now 85, by the Australian performance artist Leigh Bowery.
Christie's has described the piece as "a bold and imposing example of the stark power of Freud's realism".
The current auction record for a Freud painting was set in November 2007 when his 1992 work IB and Her Husband was sold for $19.3m (£9.3m).