Spanish police have arrested four people for trying to sell a forged Pablo Picasso oil painting for nearly £1m.

The canvas, a counterfeit version of a 1964 work called Buste de Jeune Garçon ("Bust of Young Man"), was accompanied by false authenticity documents bearing the signatures of Paloma, one of the Spanish painter's daughters, and a renowned French art expert.

Investigators sought professional advice from museum experts and determined that the real painting, which is slightly different to the offered fake, carried official certification by Maya Widmaier, the painter's oldest surviving offspring.

Spain's interior ministry said in a statement on Saturday that officers arrested three art brokers involved in the offer for sale and the current owner, a well-known Madrid antiquarian.