LOS ANGELES (Reuters) - A judge on Tuesday dismissed the charges against seven reputed gang members accused of abducting a music producer to demand the return of a supposed sex tape featuring former NBA star Shaquille O'Neal.

The dismissal came after a prosecutor told Los Angeles Superior Court Judge M.L. Villar de Longoria that the District Attorney's office had lost confidence in the credibility of the alleged victim, Robert Ross.

O'Neal, who retired from pro basketball this year after 19 seasons in the National Basketball Association, was never charged in the case or named in the criminal complaint against the seven men.

After the case was filed in February, Ross testified that he told O'Neal about a sex tape during a business dispute with the NBA star.

About two weeks later, Ross claimed, the defendants kidnapped him and demanded he return the tape, said Jane Robison, a Los Angeles District Attorney's spokeswoman.

Ross also testified that he did not have such a tape, Robison said.

That was one of a number of problems with Ross' testimony, which combined with his out-of-court behavior led to the case's dismissal, Robison said.

The criminal complaint had charged the seven reputed gang members with abducting Ross at gun point in February 2008.

It also accused the men of conspiracy, and of assaulting Ross and taking his Rolex watch, diamond jewelry and $15,000 in cash before releasing him.

As a result of the judge's dismissal of the case at the request of the seven men's defense attorneys, some of the defendants will be released from jail while others will remain in custody to face charges in unrelated cases, Robison said.

(Reporting by Alex Dobuzinskis: Editing by Greg McCune)