A lawyer for former U.S. Marine Paul Whelan, who was convicted of espionage in Russia last month, says her client's 16-year prison sentence has begun.

Olga Karlova said on July 3 that Whelan remained in the Lefortovo detention center in Moscow and it was not clear when he will be transferred to a penal colony, which usually happens after a convict's sentence takes effect.

Whelan's other lawyer, Vladimir Zherebenkov, said on June 23 that his client will not appeal his sentence, despite denying the charges, and therefore it will come into force without any delay.

He added that Whelan hopes Washington and Moscow will agree on an exchange of prisoners.

Reports in June said that Russian and U.S. officials were in talks on a possible swap of Whelan for two Russians -- Viktor Bout and Konstantin Yaroshenko -- who are serving lengthy sentences in U.S. prisons.

The Moscow City Court convicted and sentenced Whelan to 16 years on June 15 after a trial that was held behind closed doors because the evidence included classified materials, as well as due to measures to slow the spread of the coronavirus.

The United States has called the proceedings a 'mockery of justice' and demanded Whelan's immediate release.

British Foreign Secretary Dominic Raab has said he was deeply disappointed by the verdict and sentence against Whelan, who also holds British, Canadian, and Irish citizenship, and expressed 'serious reservations about the legal process.'

Russia's Foreign Ministry has rejected 'claims about the unfairness and excessive harshness' of the sentence. President Vladimir Putin's spokesman, Dmitry Peskov, said on June 23 that the Kremlin had noted Whelan's decision not to appeal his conviction but declined to comment further.

The 50-year-old Whelan was arrested in Moscow in December 2018.

Russian prosecutors claimed that a flash memory stick found in his possession contained classified information.

Whelan says he was framed when he took the memory stick from an acquaintance, thinking it contained holiday photos. He also accused his prison guards of mistreatment.

Whelan was head of global security at a U.S. auto-parts supplier at the time of his arrest. He and his relatives insist he visited Russia to attend a wedding.

Before the verdict, U.S. officials had urged Moscow to release Whelan following their criticism of Russian authorities for their 'shameful treatment' of him.

With reporting by Interfax, RBK, and TASS

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