A 24-year-old Navy enlisted man, indicted last month on charges of stealing secret Pentagon documents, was indicted yesterday by a federal grand jury in Alexandria on three similar new charges.

Lee Eugene Madsen, who pleaded innocent to the earlier charges was charged with stealing 21 additional secret reports the day of his arrest last month.

Madsen has been jailed since Aug. 14 and is scheduled to appear in court today to attempt to reduce his $250,000 bond.

According to the charges filed yesterday, Madsen on Aug. 14 took three secret Central Intelligence Agency reports from the Pentagon, where he worked as a security specialist on the Strategic Warning Staff. Two of the documents were parts of a study called, "Central America: Short-Term Prospects for Insurgency," and were dated August 1979.

Other documents listed in the new indictment involved current top-secret CIA studies of "Communist World" aircraft production, reports on Soviet naval facilities, an intelligence appraisal of the Warsaw Pack, photographic interpretation reports on naval base facilities in China and a report of a meeting involving Korea.

The documents were "concealed" at Madsen's home in Northern Virginia, according to the new indictment.

Pentagon officials have expressed concern at the apparent ease with which Madsen allegedly took the documents from the Pentagon.

Madsen is scheduled to stand trial on the earlier charges Oct. 4. Each of the 11 counts against him carries a maximum penalty of 10 years in prison and a $10,000 fine.