A court in Moscow is due to sentence Russian nuclear arms expert Igor Sutyagin after he was found guilty of spying for the United States.
Sutyagin says any information he provided was in the public domain
Sutyagin was convicted by a jury of passing information on submarines and missile warning systems to a UK firm allegedly used as a cover by the CIA.
A prosecutor recommended on Tuesday a jail sentence of 17 years.
Sutyagin's defence says he merely wrote analysis based on publicly available sources and is planning to appeal.
On Tuesday, the US State Department questioned the fairness of the closed-door trial.
"We have expressed our concerns with the way the case of... Igor Sutyagin was handled and, in particular, its lack of transparency and due process," State Department spokesman Adam Ereli said in Washington.
Sutyagin's lawyer Boris Kuznetsov told Russian news agency Itar-Tass on Tuesday that the prosecution was seeking 17 years of imprisonment in a high security facility.
Sutyagin's lawyer says he plans to appeal
Speaking as the Moscow City Court reviewed the court verdict, Mr Kuznetsov said the defence had produced "new arguments confirming his innocence".
A senior weapons control researcher at Moscow's respected USA-Canada Institute, Sutyagin has insisted he had no reason to believe he was dealing with a company used as an intelligence cover.
His conviction by closed military trial has sent shockwaves through the Russian academic world, the BBC's Steve Rosenberg in Moscow reports.
Many Russian researchers and scientists offer consultancy services to western companies as a means to bolster their meagre salaries, our correspondent notes.
Mr Kuznetsov criticised the conduct of the trial and accused the presiding judge of manipulating the jury by putting the focus on the passing of information, rather than state secrets.
"The questions addressed to the jury did not correspond to the charges," Mr Kuznetsov said.
In January, four international human rights groups said that Sutyagin was "the target of politically motivated treason charges" and urged the Parliamentary Assembly of the Council of Europe to appoint a rapporteur on his case.
"Sutyagin's case is part of a pattern of arbitrary prosecutions of independent scientists, journalists and environmentalists in Russia who work on sensitive topics," the four groups - including Amnesty International and Human Rights Watch - said.
Trial by jury
Sutyagin's trial is believed to be the first espionage case in Russia to be decided by a jury.
Sutyagin has been in prison since his arrest in October 1999.
A court had been expected to deliver a verdict in the case in February 2001 but instead instructed prosecutors to continue investigating and left Sutyagin in jail.
Mr Sutyagin's trial is one of a series of high-profile spy cases against Russian researchers:
- Valentin Danilov was cleared of spying for China in December
Military reporter Grigory Pasko was released in January 2003 after serving two years for treason after disclosing how Russia had dumped nuclear waste in the Pacific Ocean
Alexander Nikitin, an environmentalist, was acquitted in 1999 of treason after contributing to a Norwegian report on radioactive pollution in the Arctic seas