"(Paul) Whelan will not appeal. He does not believe in Russian justice," his lawyer Vladimir Zherebenkov told news agency Interfax.

"He hopes that in the near future he will be exchanged with Russians convicted in the United States."

The 50-year-old, who also has British, Canadian and Irish passports, was last week sentenced to 16 years in a penal colony despite diplomatic protests.

His trial strained ties with Washington and fuelled speculation of an exchange with Russians detained in the United States, including pilot Konstantin Yaroshenko, who is imprisoned on drug smuggling charges, and arms dealer Viktor Bout.

"We know there are negotiations, everyone talks about them behind the scenes, but we ourselves aren't participating in them," Zherebenkov told news agency RIA Novosti.

He said that details of a swap would only become clear "when an agreement is reached".

Whelan was detained in Moscow in late 2018 and insisted he was innocent of receiving state secrets throughout his trial, which was held behind closed doors.

He says he was detained on a visit to Moscow to attend a wedding when he took a USB drive from an acquaintance thinking it contained holiday photographs.

US Secretary of State Mike Pompeo slammed the verdict and demanded that Russia release Whelan immediately, while US ambassador to Moscow John Sullivan condemned the trial as unfair and lacking transparency.

David Whelan, Paul's brother, said ahead of the trial that the family hoped a conviction would allow Russia and the United States to "begin discussing Paul's release immediately".