NEW YORK, Oct 3 (Reuters) - Dan Och and other former Sculptor Capital Management executives on Tuesday urged the hedge fund to release details about a sweetened rival takeover bid reportedly larger than its agreed sale price of around $639 million in July.

Investors Boaz Weinstein, Bill Ackman, Marc Lasry and Jeff Yass - members of a group called Bidder J - recently raised their bid from a previous $12.76 per share, sources familiar with the matter said.

However, Sculptor, which oversees $30 billion in assets and is the biggest U.S. publicly traded hedge fund, has chosen to stick with Rithm Capital Group's $11.15 per share bid. Bloomberg on Monday reported that Rithm has held talks with Sculptor about increasing its offer.

"At a minimum Sculptor should disclose the facts as the stock is trading and shareholders have a right to know," Och and the others said in a statement to Reuters.

"Based on what we have read, we believe that the revised offer is more attractive than the $11.15 Rithm deal."

Sculptor's stock climbed more than 7% on Tuesday to end at $12.22.

A representative of Sculptor was not immediately available for comment.

Och again called on the hedge fund to release parties from their non-disclosure agreements, repeating calls he has been making for weeks, and urged Sculptor to engage with Weinstein's group for the sake of shareholders.

"We call on the special committee to release parties from their NDAs, engage with the Weinstein group and act in the best interests of shareholders," Och said in the statement.

The back and forth between some of the hedge fund industry's most storied investors is making for one of this year's most closely watched investment dramas. Weinstein runs Saba Capital Management, Ackman runs Pershing Square Capital Management while Lasry runs Avenue Capital Group and Yass founded Susquehana International Group.

Rithm has said that it would keep Sculptor's leadership team, including chief investment officer Jimmy Levin. The Weinstein bid would have the assets overseen by an office of the chief investment officer and not have Levin continue in a long-term role at the company, according to regulatory filings.

Och, who founded the firm originally called Och-Ziff Capital Management in 1994, had once planned for Levin to become his successor at the firm but then changed his mind. (Reporting by Svea Herbst-Bayliss; Editing by Richard Chang and Stephen Coates)