Spain's wealthiest woman is robbed of valuable artworks

An international hunt was underway on Thursday night for art thieves who stole paintings worth about £35m from the home of one of Spain's wealthiest women.

The robbers are said to have forced their way into the Madrid home of Esther Koplowitz, a prominent society figure, gagged a security guard and got away with 14 valuable works. The stolen paintings included works by Goya, Gris, Pisaro and Brueghel.

The robbers rang the bell to Ms Koplowitz's residence – which is under construction – in the wealthy neighbourhood of Chamartin, and assaulted the guard who answered the door,

The guard told investigators that the intruders overpowered him, then tied and gagged him as they went to collect their loot. Ms Koplowitz was on holiday at the time but she contacted the police when she heard about the robbery.

The national news agency, Efe, said that police were not ruling out an inside job.

The missing pieces include The Donkey's Fall and The Swing by Francisco de Goya, and The Temptations of St Antonio by Pieter Brueghel, all valued at about £7m each. Juan Gris's Guitar on a Chair and Camille Pisarro's Landscape at Eragny were also stolen, along with a number of unidentified sculptures.

Spanish media said Interpol has issued an international bulletin on the stolen artworks.

Mrs Koplowitz, 52, has a 56 per cent stake in Fomento de Construcciones y Contratas, the largest Spanish construction firm with sales totalling 743 billion pesetas (£2.6bn). She holds the title of Countess of Casa Penalver and Cardenes de Monte Hermoso.

Forbes magazine listed Esther and her sister, Alicia Koplowitz, as the 490th richest people in the world this year, with fortunes estimated at 200 billion pesetas (£700m) each. That made them the two wealthiest women in Spain.