Thousands of fans swamped a website to register for free tickets to a memorial service for Michael Jackson in Los Angeles, as squabbles continued over custody of his children and more evidence of drug abuse emerged.

The service will take place at the Staples Centre, in downtown Los Angeles, after a funeral attended by family and close friends. The centre, which seats 20,000, was used by Jackson in the days before his death to rehearse for a run of 50 shows in London that had been due to start this month.

Fans have until 6pm today to register for the service on the website staplescentre.com. A lottery will decide who will qualify for the 17,500 tickets on offer, which will be allocated in pairs to US residents. The service will be shown live on television and police and organisers warned all those without tickets to stay away.

A spokesman for the Jackson family declined to comment on whether Debbie Rowe, Jackson’s former wife and mother of his two eldest children, would attend the private funeral. She is considering contesting custody of the children, who have been put under the temporary custody of the singer’s mother, Katherine Jackson. A court hearing on the matter in Los Angeles has been put back to July 13.

Ms Rowe told a TV news reporter that she wanted to keep Jackson’s father, Joe, away from his grandchildren. He has admitted whipping his children with a belt when they were young. He is still married to Katherine, though the couple are separated.

Further details emerged yesterday of Jackson’s alleged abuse of painkillers and other prescription drugs. The powerful sedative Diprivan was found in the rented mansion in Los Angeles where he died. The discovery reinforces claims from a nutritionist treating Jackson that he claimed to have been given a powerful sedative for insomnia before his death.

Cherilyn Lee said she repeatedly rejected his demands for the drug, which is used in operating theatres and is given intravenously. Jackson told her that he had been given it in the past by an unnamed doctor. The drug has a very narrow therapeutic window, meaning doses not much larger than the medically recommended amount can stop a person’s breathing, leading to cardiac arrest.

The Los Angeles coroner’s office performed an autopsy on Friday but deferred a decision on the cause of death, ordering toxicology tests. A second private autopsy has been requested by the family.

AEG, which runs the Staples Centre, plans to release a video and DVD taken from 100 hours of footage of rehearsals for the This Is It planned shows in London. It is expected that Jackson will be buried at Forest Lawn Memorial Park, where Humphrey Bogart, Sammy Davis Jr and Nat “King” Cole are buried. The family had hoped to bury at the Neverland ranch in Santa Barbara County but had difficulties in obtaining a permit.

Jackson’s rented mansion is to be turned into a memorial site. Christian Audigier, the French fashion mogul, announced he would buy the building.

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