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By Daniel Bases

NEW YORK, Nov 3 (Reuters) - Daniel Pollack, the court-appointed mediator in the debt dispute between Argentina and holdout creditors, has been given broad authority to grant other investors a seat at the negotiating table in an effort to agree on a comprehensive settlement.

U.S. District Judge Thomas Griesa issued the order on Monday giving Pollack, known officially as the Special Master, the power to choose other investors, who have sued Argentina in hope of securing better settlement terms, to any future negotiating sessions.

This order could mute some of Argentina's criticism of the requirement that settling the dispute must be with all bondholders not just the specific holdouts in the case assigned to Pollack.

"In recognition of the complexities created by adding such additional cases, the court hereby confirms that the Special Master shall have broad authority to structure the arrangements for such negotiations, as between and among the plaintiffs, as he shall determine in his sole discretion best suited to effect settlement of litigation with the defendant, the Republic of Argentina," Griesa's order says.

There are roughly 60 cases filed to Griesa's courtroom alone in the U.S. Southern District court with approximately $10 billion worth of claims by investors who did not accept Argentina's restructuring offers in 2005 and 2010, according to one source familiar with the situation.

The holdout investors are led by NML Capital, an affiliate of billionaire Paul Singer's Elliott Management and Aurelius Capital Management, led by Mark Brodsky, formerly of Elliott.

In 2012 Griesa issued an injunction forbidding financial institutions from transferring government payments to so-called exchange bondholders without also paying the NML/Aurelius group their court awarded $1.33 billion plus accrued interest.

Exchange bondholders accepted restructurings that paid roughly 30 cents on the dollar. The holdouts claimed in June the accrued interest has pushed their award to approximately $1.65 billion.

Pollack was appointed by Griesa on June 23, one week after the U.S. Supreme Court declined to hear Argentina's appeal of the decision, effectively exhausting its legal recourse in the case that stems from the nation's historic sovereign debt default in early 2002.

It was unclear when the next negotiation meeting would take place. Pollack declined to comment when reached by Reuters. Representatives of the holdouts were not immediately available.

As the July 30 deadline for a default ticked closer, Pollack got the two sides to a first-time face-to-face meeting. Ultimately the talks failed and Argentina defaulted.