Thieves apparently smashed ancient Greek vessel they were trying to steal from Golders Green crematorium in north London

An attempt has been made to steal the remains of Sigmund Freud – or more plausibly, the ancient Greek urn in which the ashes of the father of psychoanalysis, and those of his wife, Martha Bernays, were interred at a crematorium in north London.

Staff at the crematorium in Golders Green discovered broken pieces of the urn, which dates from around 300BC and came from Freud's collection of antiquities, lying on the floor on New Year's Day, after thieves apparently broke in overnight and smashed it in the attempt to steal it.

The urn had been on public display since Freud was cremated at Golders Green in 1939, after his death aged 83. When his widow died in 1951, aged 90, her ashes were added.

The urn – like the famous couch in his consulting room – was a gift from one of his many aristocratic patients. Knowing of Freud's interest in the art of ancient Greece, it was a gift from Princess Marie Bonaparte, great grandniece of Napoleon, who herself became a psychoanalyst, and who helped the Freud family escape from Vienna in 1938 as the Nazi grip tightened.

The graceful, classically draped figures, painted against a glossy black background, celebrate life and depict Dionysus and a maenad (a follower of the god of wine and revelry). It was specially chosen by his family to house his ashes.

Detective Constable Daniel Candler called theft attempt as "a despicable act".

"Even leaving aside the financial value of the irreplaceable urn, and the historical significance of to whom it related, the fact that someone set out to take an object knowing it contained the last remains of a person defies belief."

Dawn Kemp, director of the museum in Freud's former Hampstead home, said: "It's a sad sad thing. It's very much a matter for the family, but Freud is very close to our hearts here, and we are deeply saddened at the news, whatever the motive was."

Writer and campaigner Lisa Appignanesi, who is chair of the trustees, described the urn as irreplaceable.

"It had been in his study for many years in Vienna, before the Nazi occupation forced the family exodus to England, to which he came, as he said, to die in freedom," she said.

Staff at the crematorium said the urn was severely damaged, and had now been moved to a secure location. Security at the site is being reviewed.

In beautiful grounds and buildings including a listed mausoleum designed by the architect Edwin Lutyens, Golders Green also holds the ashes of scores of famous names including Bram Stoker, the creator of Dracula, and fellow authors Enid Blyton and Kingsley Amis, the ballerina Anna Pavlova, the rock star Marc Bolan, the former prime minister Neville Chamberlain, the playwright Joe Orton, and the actors Sid James and Peter Sellers.

One of the most recent high-profile funerals, earlier this month, was of the Great Train Robber, Ronnie Biggs.

Freud, born in 1856, escaped Vienna with his family in 1938, finding sanctuary in London. His consulting room in Hampstead still holds his oriental carpet draped couch, on which some of the most famous patients in the history of psychiatry lay and revealed their traumas, including "wolf man", "Dora" and "rat man".

He was also keen on archaeology and the antiquities of ancient Egypt and Greece, and kept a large collection of artefacts in his study, including an array of little statues of gods and cult figures on his desk.

Freud's grandchildren included the painter Lucian and the politician and author Clement, while the present generation includes the PR guru Matthew, who is married to Rupert Murdoch's daughter Elisabeth, and Emma, Esther and Bella, broadcaster, novelist and fashion designer respectively.