Robert Hanssen, a veteran FBI counterintelligence agent, was indicted by a federal grand jury Wednesday on charges of spying, causing "grave injury to the security of the United States."

Hanssen, who was arrested by federal agents while allegedly delivering a package for pickup in a northern Virginia park, was indicted on one count of conspiracy to commit espionage, 19 counts of espionage and one count of attempted espionage, the Justice Department said.

Hanssen was only the third FBI agent ever accused of espionage.

At the time of his arrest in February, the FBI said that Hanssen, 57, had passed along to Soviet and later Russian agents 6,000 pages of documents on secret programs that described how the United States gathers intelligence, technologies used for listening, people who work as double agents and other highly sensitive matters. The bureau said this activity occurred over a 15-year period starting in 1985.

The conspiracy count and the espionage charges carry a maximum penalty of death or life imprisonment. Each charge also carries a potential fine of not more than $250,000 or double what Hanssen gained from the alleged spying.

Discussing the indictment on the steps of the U.S. Courthouse in suburban Alexandria, Va., U.S. Attorney Ken Melson refused to comment on the impact the indictment would have on plea negotiations between Hanssen and the government.

"I can't comment on any plea negotiations or the existence of them or the status of them," Melson told reporters, a day after Hanssen's lawyers confirmed that such talks had stalled.

Melson also said the 21-count indictment was filed Wednesday -- five days before a scheduled hearing for Hanssen -- because "the grand jury sits this week and does not sit on Monday."

The indictment came after plea discussions between Hanssen's lawyers and federal prosecutors broke down over the issue of the death penalty. Hanssen's lawyers said the government wanted Hanssen to provide information about what secrets he revealed but would not agree to waive the death penalty in exchange for the information. Hanssen's lawyers have said Hansen will plead innocent.

An arraignment was scheduled for June 1.

The indictment alleges that Hanssen "betrayed his country for over 15 years and knowingly caused grave injury to the security of the United States," Melson said.

The indictment charges Hanssen with conspiring with officers of the KGB and its successor intelligence agency, the SVR, to deliver to Moscow "information relating to the national defense of the United States" with the intent of harming the United States and benefiting Moscow, the Justice Department said.

The indictment also says that Hanssen's spying led to the identification by Moscow of U.S. agents and consequently in the deaths of two of them.

The indictment seeks $1.4 million from Hanssen that he allegedly received in cash and diamonds, along and two Rolex watches. It alleges the spying began on Oct. 1, 1985, and continued until his arrest.

Among the highly classified documents and information Hanssen allegedly revealed: satellites, early warning systems, means of defense or retaliation against large-scale attack, communications intelligence and major elements of defense strategy, the Justice Department said in a statement.

Melson said, "We will continue to vigorously pursue this case until Mr. Hanssen is properly brought to justice."

Hanssen attorney Plato Cacheris had said Tuesday that he expected his client to be indicted. "We felt they had more than enough time to resolve the issue of the death penalty. We do not think the death penalty is justified."

Hanssen's lawyers rejected the government's offer to extend the discussions for another 30 days.

A preliminary hearing in the case had been scheduled for Monday, the deadline for the grand jury to hand down an indictment.

The FBI began investigating Hanssen only last year. He has been held in jail at an undisclosed location.