Michael Jackson's doctor realised the singer had some “very unusual problems”, but only after he began working with the star, his lawyer has said.

Ed Chernoff told the Los Angeles Times his client did not know whether Jackson was taking any medication or if he suffered from addiction problems.

"When he accepted the job, he was not aware of any specific requirements regarding medications that Michael Jackson was taking or any addictions that he was suffering from," Chernoff said.

Dr Conrad Murray moved to Los Angeles in May after he was hired as the singer's personal physician for his comeback shows in London.

It was then when "he realised that Michael Jackson had some very unusual problems,” Mr Chernoff said.

Meanwhile, Chernoff's spokeswoman Miranda Sevcik told CNN Dr Murray did not conduct drug tests on the singer and would not have known if the star was taking any medication unless Jackson himself had told him.

Dr Murray's Houston and Las Vegas offices have been raided as part of the police manslaughter investigation into Jackson's death on June 25.

US media reports have claimed the singer took the drug propofol shortly before he died.

But Mr Chernoff has previously dismissed claims that Dr Murry gave Jackson the drug.

The toxicology report into Jackson's death has been completed, but the results are being kept secret while the investigation is ongoing.

(by Jason Gregory)