WASHINGTON - A government space scientist accused of trying to sell secrets to Israel has reached a plea deal with prosecutors.

Attorneys involved in the case would not discuss the agreement that Stewart David Nozette reached. U.S. District Judge Paul Friedman scheduled a hearing Wednesday morning to take Nozette's plea.

Nozette was arrested almost two years ago and has been held in jail because prosecutors said he was a "walking safe deposit box" of government secrets and convinced a judge that he was a flight risk. He has been charged with four counts of attempted espionage that could carry the death penalty, and he initially pleaded not guilty.

Prosecutors accused him of seeking $2 million to sell secrets to an undercover FBI agent posing as an Israeli intelligence officer in a videotaped sting operation.

Nozette had high-level security clearances during decades of government work on science and space projects at NASA, the Energy Department and the National Space Council in President George H.W. Bush's White House. He has a doctorate in planetary sciences from the Massachusetts Institute of Technology and was known primarily as a defence technologist who had worked on the Reagan-era missile defence shield effort formally named the Strategic Defence Initiative. He also helped discover evidence of water on the moon.

Because he knows so many secrets, including about the nation's nuclear missile program, Attorney General Eric Holder ordered special communications restrictions placed on him in jail.

During a hearing after his arrest, the prosecutor played video from the September 2009 sting in which Nozette lounged on a hotel room couch, eating and laughing with the undercover agent. He discussed the possibility of having to flee the country if he came under scrutiny.

Prosecutors say Nozette agreed to provide regular information to the Israeli intelligence agency, Mossad, through a post office box in exchange for money. They accuse him of asking for an Israeli passport and payments in cash under $10,000 each to avoid reporting it. Authorities said he took two payments, one for $2,000 and another for $9,000, from the post office box to answer questions about U.S. satellites, including early warning systems, means of defence or retaliation against large-scale attack, communications intelligence information and major elements of defence strategy.

Nozette also ran a non-profit corporation, called the Alliance for Competitive Technology, out of his Chevy Chase, Maryland, home. It had several agreements to develop advanced technology for the U.S. government. In January 2009, he pleaded guilty to two counts of tax evasion and admitted overstating his costs for reimbursement and failing to report the income on his tax returns. His sentencing in that case has been held while the espionage charges have been pending.