UPDATE 1-U.S., Madoff agree to delay any indictment-source

(Adds background on case)

NEW YORK, Feb 11 (Reuters) - The filing of any criminal indictment against Bernard Madoff has been delayed at the request of both prosecutors and the accused swindler's defense team, a person close to the matter said on Wednesday.

The agreement, which has yet to be formally filed in federal court in Manhattan, calls for a 30-day extension of Wednesday's deadline to bring an indictment, the source said. A similar extension in the case was agreed to in January.

Madoff was charged in a criminal complaint in December with fraud after federal authorities said he confessed to a long-running swindle that cost investors $50 billion.

He has been under house arrest in his Manhattan penthouse as authorities continue to probe the case.

A spokeswoman for the U.S. Attorney's Office in Manhattan, which is prosecuting the case, was not immediately available for comment.

The Wednesday deadline had been the date for the government to persuade a federal grand jury to bring an indictment against Madoff, a former chairman of the Nasdaq stock market and once a respected money manager.

It is not unusual for such deadlines to be extended as prosecutors and the defense discuss ways to resolve a case. Madoff's lawyers have said their client is cooperating with government investigations into the alleged swindle. (Reporting by Martha Graybow; editing by John Wallace)