Eva Rausing's husband Hans, an heir to the Swedish Tetra Pak packaging fortune, appeared at the hearing in west London to respond to a charge of preventing the "lawful and decent" burial of his 48-year-old wife.

Rausing, with a neatly trimmed beard and wearing a dark blue blazer, only spoke to plead guilty to that charge and to a charge of driving while unfit through drugs.

Police found his wife's body in an advanced state of decomposition under layers of clothes and bin liners in a fly-infested room at their six-storey townhouse in Cadogan Place in central London.

Officers made their grim discovery on July 9 after stopping Rausing, 49, for driving erratically and arresting him on suspicion of driving under the influence of drink or drugs.

The court was told a post-mortem had established that his wife had died more than two months earlier, on May 7, and had drugs, including cocaine, in her system.

Rausing told police in a statement after his arrest that he had not supplied his wife with drugs and believed he had suffered "some form of breakdown" since her death, the court heard.

"I do not have a very coherent recollection of the events leading up to and since Eva's death. Safe to assure you that I have never wished her or done her any harm," Rausing said.

"I do not feel, with the benefit of hindsight, that following her death I acted rationally," he added, the Press Association reported.

The couple, who have four children, first met at a U.S. drug rehabilitation centre and gave generously to addiction treatment centres.

Eva Rausing's family have said they believe Eva turned to drugs in her late teens to overcome acute shyness.

Hans Rausing's parents said last month they hoped he would find the strength to "begin the long and hard journey of detoxification and rehabilitation".

Rausing had earlier been on bail on condition he remain at a private mental hospital in London.

The Rausing family fortune was made by building up and then selling the Tetra Pak drinks packaging business. The wealth of the Swedish family's patriarch, also called Hans Rausing, is estimated at $10 billion by Forbes magazine.