Russia complained about spy in 1993

WASHINGTON (CNN) -- Russia complained in 1993 that one of its intelligence agents had been approached by someone offering to sell U.S. secrets, sources say a report on the Robert Hanssen spy case documents.

The report, to be presented Tuesday to a Senate panel investigating the affair, is said to cite the complaint as a missed opportunity for U.S. authorities to try to plug the leak later linked to Robert Hanssen, a 25-year FBI veteran who was eventually arrested in February, 2001.

Hanssen pleaded guilty in July to 15 counts of espionage for giving information to the Soviet Union and later Russia, dating back to 1979. Under his plea agreement, he is expected to receive a sentence of life in prison without the possibility of parole.

U.S. government sources familiar with the report told CNN on Thursday that the identity of the person offering intelligence information was not yet known when Moscow filed the complaint. It was filed about eight years before Hanssen's arrest on a long list of charges related to espionage activities over a period of about 20 years.

The report, put together by a panel headed by William Webster, former chief both the FBI and the CIA, is expected to be delivered Friday to U.S. Attorney General John Ashcroft. Webster is to appear Tuesday before the Senate Judiciary Committee to talk about the report.

The report is expected to be highly critical of the FBI's security procedures.