Los Angeles (CNN) -- Michael Jackson's mother and four of his siblings announced Monday a tribute concert for the late pop singer to be held in Wales in October, but the lineup for talent is still a secret.

Brothers Marlon, Tito and Jackie, sister La Toya and family matriarch Katherine Jackson attended the "Michael Forever The Tribute Concert" announcement at the Beverly Hills Hotel on Monday morning.

But the announcement exposed a major rift among members of the Jackson family, especially with Jackson brothers Jermaine and Randy, who did not attend the news conference. They objected to the show because it's scheduled to happen during the criminal trial of the doctor accused in Michael Jackson's death.

"We want to make clear that this does not reflect the position of the entire family," the two brothers said in a joint statement. "While we wholeheartedly support the spirit of a tribute that honors our brother, we find it impossible to support an event that is due to take place during the criminal trial surrounding Michael's death," they said.

While the head of the British company promoting the show, Global Events Live, hinted it could include a Jackson brothers reunion, the statement from Jermaine and Randy Jackson on Monday indicated that would not happen.

"In light of this, we feel it is inappropriate to be involved with such an ill-timed event and its promoter, Global Live," Randy and Jermaine Jackson said.

Their statement said the idea of the October concert was presented to the entire family in April "as an idea already in its advanced stages." The decision to go ahead with it "disrespects opinions and wishes expressed in the strongest terms" by some members of the Jackson family, they said.

La Toya Jackson said the "tribute will be something that's spectacular" and is "far, far, well overdue.'

The Jacksons' mother called it "a show fit for a king,"

"If my son were here today, he would feel the same way," Katherine Jackson said.

Executors for the late pop singer's estate were unaware of the planned tribute, estate spokesman Jim Bates told CNN.

"The estate has not been contacted and is not involved with Global Live Events in the UK tribute concert announced today," he said.

The show will "feature the world's most amazing music performers," according to the head of British promoter Global Live. The roster will be revealed online one act at a time over the next two weeks, starting Tuesday, Chris Hunt said. All profits from the show would go to several U.S. and British charities, including a cancer group created by the prince of Wales, Hunt said.

The October 8 show, in the Wales Millennium Centre in Cardiff, Wales, would be at least four hours long, Hunt said. The venue will seat up to 75,000 people, he said.

"I know my brother would be very, very proud to see all the artists that he admired and respected so much coming together for this event," Tito Jackson said.

Hunt presented the Jackson family with a $100,000 check that will go to a trust fund for Michael Jackson's three children, which they can access when they turn 21. The children, Katherine Jackson and unidentified charities are the sole beneficiaries of Jackson's wealthy estate.