IT WOULD be illegal for the British Museum to return art- works looted by the Nazis to a Jewish family, despite its "moral obligation" to do so, a High Court judge ruled yesterday. Vice-Chancellor Sir Andrew Morritt ruled that the British Museum Act - which protects the collections for posterity - cannot be overridden by the ethical merit of a claim involving plundered art. The heirs of the art's original owners, Dr Arthur Feldmann, a Czech lawyer, and his wife Gisela, who died at the hands of the Nazis, said they were "very upset" at the ruling. They called on the government to introduce legislation that would allow the pieces - four Old Master drawings stolen from the family home in Brno by the Gestapo in 1939 - to be returned to them swiftly. Lawyers for the British Museum, which had agreed in principle three years ago to the restitution of the drawings to the family, also said they were "disappointed" by the outcome of the test case. Anne Webber, the co-chair of the Commission for Looted Art in Europe, which is representing Dr Feldmann's heirs, said the ruling had "prolonged the agony of a family who have already suffered". "The family are very upset by the outcome but nevertheless they have confidence in the British Museum's commitment to restitution. The government needs to move swiftly."