Michael Jackson's parents, Katherine and Joseph Jackson, are to examine the contract their son signed for his comeback shows in London, it's been claimed.

The pair are reported to have hired private investigators amid claims Jackson had only agreed to play ten shows at the O2 Arena, and not the scheduled 50.

The singer's parents are also considering wrongful death lawsuits, according to The Sun newspaper.

On Monday, a Los Angeles judge overturned an original ruling which barred Katherine, 79, from seeing the contract her son had signed with promoters AEG Live.

Jackson, who died on June 25, was set to begin his gigs in London on July 13.

"Joe has been obsessed with AEG's role from the start and wanted to see the contract,” a source told the newspaper.

“Joe didn't trust them and told Michael. He is adamant he only agreed or wanted to do ten shows and was pressured into doing more."

The Jackson family are understood to be keen to look into the circumstances surrounding Jackson's death, including the role of his doctor, Conrad Murray.

The star had also been given a clean bill of health to perform in London just weeks before his death.

(by Jason Gregory)