The clamour for tickets for Michael Jackson's public memorial began last night but the singer's British fans will be disappointed.

Only US residents with tickets secured through an online ballot will be allowed in to the Staples Center in Los Angeles.

Other fans of the King of Pop will be able to watch Tuesday's event from their homes as organisers announced it will be broadcast around the world.

The stadium's website temporarily crashed within moments of AEG Live president and chief executive Tim Leiweke announcing the opening of registration for the draw.

He said 17,500 free tickets will be available in pairs for Jackson's fans — 11,000 of which will admit entrance to the Staples Centre itself, with 6,500 places to watch on screens at the nearby Nokia theatre.

Registration will end at 2am Sunday morning BST, with the 8,750 successful applicants drawn at random and then notified by email between 7pm Sunday to 4am Monday BST.

Mr Leiweke said: “First off, our thoughts and prayers are with the family, all of the Jackson family, and in particular with Michael Jackson's fans.

“It is the family's wish to create a service and a celebration that all of Michael's fans around the world can be part of. Thus, the family has made arrangements to provide a worldwide pool feed to every network for free.

“The family has also made available 17,500 tickets for Michael's fans to be part of this service.”

No information was given about what the memorial service will involve or celebrities who might appear. Jackson's legion of fans have been descending on Los Angeles since his sudden death at the age of 50.

City officials told last night's press conference that they were encouraging people to stay away unless they had tickets for the memorial as strict checks would be in place.

Details emerged as a law enforcement official said the powerful sedative Diprivan was found in Jackson's home.

Diprivan is an anaesthetic widely used in operating theatres to induce unconsciousness.

Also known as Propofol, it is administered intravenously and is very unusual to have in a private home. Jackson died on June 25 after suffering a suspected cardiac arrest.

Footage of the singer rehearsing at the Staples Centre two days earlier was released on Thursday.

The star appeared in full flow as he danced around the stage in typical fashion to some of his most famous hits for the final time.

He was preparing for his 50-night residency at London's O2 arena, which had been due to begin later this month.

Uri Geller, a friend of the singer, said the footage raised a “big question” about what prompted the star's dramatic demise.

“The question is: What happened from that point to the day that he died?” said Geller. “In the photographs I've seen, he looked in shape, he was smiling, he was happy. What happened? That's the big question.”

Kevin Mazur (48), the photographer who captured some of Jackson's final moments on camera at the rehearsals, said the star appeared to be back to his best and had an “incredible energy”.

Mr Mazur, co-founder of WireImage, told the Daily Mirror: “When he hit that stage, everyone was just mesmerised.”

The photographer said Jackson was happy and joking with the dancers as he rehearsed.

He told the newspaper that Jackson performed his set for 90 minutes until nearly midnight on June 23.

“He was totally there — 100% there, in fact,” said Mr Mazur. “You would never suspect this would have happened — especially after his performance on stage.”

It emerged yesterday that America's anti-drugs agency had launched an investigation into Jackson's death.

The Drug Enforcement Administration (DEA) was called in by Los Angeles police to assist as they probed allegations that the star was on powerful painkillers, sedatives and anti-depressants, sources close to the investigation said.

As Jackson prepared for the comeback concerts, he was so distraught over persistent insomnia that he pleaded for Diprivan, according to Cherilyn Lee, a nurse who was working with the singer.

She said she repeatedly rejected his demands because the drug was unsafe.

Jermaine Jackson said he would be “hurt” if toxicology reports showed that his brother had abused prescription drugs.

He told NBC he did not know of any drug abuse by the 50-year-old.

But he added: “In this business, the pressure and things that you go through, you never know what one turns to.”

Meanwhile, a US judge delayed a guardianship hearing for Jackson's children until July 13.

The ruling was made at the request of lawyers acting for the singer's mother and his ex-wife, Deborah Rowe. It had been due to take place on Monday.

Lawyer Eric M George said Ms Rowe had not reached a final decision on whether to seek custody of the two children she had with Jackson. Jackson's mother, Katherine, will retain temporary guardianship of the children until the hearing.