An heir to the multibillion dollar Tetra Pak packaging family has been arrested in connection with the death of his wife, whose body was found at their luxurious west London home, according to reports.

The body of Eva Rausing, 48, was discovered by detectives in an upstairs bedroom at the couple's five-storey Georgian townhouse in Cadogan Place, Belgravia, one of London's most exclusive streets, the Guardian newspaper reported.

Police said the property had been searched following the earlier arrest in south London of a 49-year-old man on suspicion of possession of drugs.

The man was later rearrested in connection with the death, which was being treated as "unexplained" but was thought to be the result of a drugs overdose.

Police have yet to confirm the man's identity, but he is widely believed to be Hans Kristian Rausing, whose Swedish grandfather Ruben Rausing invented the Tetra Laval milk carton in the 1960s.

The couple had struggled for many years with addiction to hard drugs, narrowly escaping prison in 2008 after heroin and crack cocaine were found at their home.

Mrs Rausing had been arrested after trying to smuggle several wraps of cocaine into a reception at the American embassy in Grosvenor Square.

The couple met in the 1980s when they were both being treated at a US drug rehabilitation centre.

Mr Rausing's father, Hans Sr, moved the family to Britain in the 1980s to avoid Sweden's higher tax regime, and in 1996 sold his half of the Tetra Pak company to his now late brother Gad for almost $10 billion.

Hans Sr, now in his 80s, lives in a 365-hectare East Sussex estate, where he raises deer and collects vintage cars and is thought to have a personal fortune worth almost $11 billion.

Hans Kristian has two sisters, the older of whom, Lisbet, studied at Berkeley and Harvard and went on to be a research fellow at Imperial College.

Sigrid Rausing, his other sister, owns the literary magazine Granta and the publishing firm Portobello books, and is a noted philanthropist.

The Telegraph said Mrs Rausing, who was born Eva Kemeny, was the daughter of a wealthy Pepsi Cola executive.

The Kemeny family live on Hilton Head Island, an idyllic spot off South Carolina known for its beaches and annual wine tasting festival.

Mr and Mrs Rausing had shared their time between London and Barbados, where they owned an 11 bedroom beachfront mansion worth $30 million.

They have four children, aged between 11 and 17, who attend a private school in East Sussex, just 25 minutes from Hans Sr's estate.

They donated millions to charity and lent their support to several organisations that support people struggling with addiction.

- © Fairfax NZ News