UPDATE 1-Jackson family supports tribute concert - brother

* Michael Jackson family backs tribute gig, organiser says

* Stevie Wonder, R. Kelly may perform, says Jermaine Jackson

* Denies reports that two top stars won't be able to make it

(Adds quotes, breaking into tears)

By Robin Pomeroy

LONDON, Sept 9 (Reuters) - Jermaine Jackson denied on Wednesday rumours that other members of the Jackson family oppose the concert he plans to stage in Vienna later this month in memory of his brother Michael.

Jackson also dismissed reports that two of the biggest stars he has lined up for the Vienna concert would not show and said he hoped Stevie Wonder would also play the Sept. 26 gig, to be staged in front of Vienna's Schoenbrunn castle.

"I invited my mother, I invited my brothers and sisters as well," he told a news conference in London. "I am not happy with the talk being said in the press about the support isn't there. My mother from the very start supported this."

Jackson himself aims to perform a virtual duet with his late brother who died from a drug overdose on June 25, weeks ahead of a planned marathon series of stadium concerts in London.

Showbiz websites have speculated the show could bomb because the few big names so far announced might not be able to make it.

Jackson confirmed that singer Mary J. Blige would be busy at a fashion event in Italy on the day of the concert, but that she would fly in to perform in its second half.

R&B star Chris Brown, who is on probation for assaulting his ex-girlfriend, the pop star Rihanna, will perform if allowed to leave the United States.

"He wants to be here. It's just up to what he's going through with his court case right now," Jackson said. "He's definitely going to be here."

When asked whether Brown's well publicised assault would lower the tone of the concert, he replied: "Not at all. And I'll tell you why. He's asked for forgiveness. ... He's a wonderful performer and during these times people need support."