TORONTO -- Global Affairs Canada says Russia is using its judicial system as a “political tool” after a U.S.-Canadian citizen was sentenced Monday to 16 years in a maximum security prison colony.

“We are deeply concerned by the conviction of Paul Whelan by a Russian court and by the severe sentence imposed on him,” a spokesperson said in an email to CTVNews.ca.

“The severity of the sentence clearly demonstrates that Russia is using its judicial system as a political tool. Canada calls upon Russia to ensure a fair and transparent appeal process free of political interference.”

The statement comes after Paul Whelan’s twin brother, David Whelan, accused the Canadian government of silence in an interview with CTV News Channel on Monday.

Paul Whelan has maintained his innocence since he was arrested in December 2018 outside a Moscow hotel on espionage charges. 

Whelan, a corporate security executive from Michigan who holds British and Irish citizenship in addition to U.S. and Canadian, was reportedly in Russia to attend a friend’s wedding at the time of his arrest. His lawyers say the charges of spying for the U.S. stem from a sting operation.

Whelan, 50, has decried the prison conditions in Russia and reportedly underwent surgery last month for a hernia. His brother told CTV News Channel that the Canadian Embassy in Moscow has been “terrific,” bringing Whelan fresh fruit and vegetables, which aren’t provided in prison. 

But that’s as far as the Canadian government response stretched, he said. 

“The government here and the lack of response even from my MP when I’ve emailed is really disappointing,” he said on a video call from Newmarket, Ont. “You would expect that your country -- the one that gives you your passport -- would then defend you when you leave your country. Apparently that’s not the case in Canada.”

In the emailed statement, Global Affairs Canada said it would “continue to provide consular assistance to Mr. Whelan and his family.” 

David hasn’t spoken to his brother since Canadian Thanksgiving in 2018, he added on CTV News Channel, though Paul was finally granted his first phone call last month after a court order. He spoke with their parents for about 15 minutes.

His brother’s sentence is “extremely harsh,” David insisted. The family and lawyer have said that there was a political motive to the trial, which was conducted in Russian and behind closed doors -- to increase Whelan's value in trades for convicted Russians in the U.S. Following the verdict on Monday, his lawyer Vladimir A. Zherebenkov said that the defence team had already received offers for exchanges. 

“It will be up to the Kremlin to offer an exchange,” Mr. Zherebenkov said, according to the New York Times, adding that the Kremlin would likely seek the U.S. release a Russian arms dealer or convicted drug dealer in exchange.

American officials have come out against Russian authorities for the treatment of Whelan, including U.S. Ambassador John Sullivan, who told reporters after the verdict that the​ conviction and sentencing was "a mockery of justice" and called for his immediate release. Secretary of State Mike Pompeo called the situation "appalling," adding that the U.S. was "outraged" by the conviction "after a secret trial, with secret evidence, and without appropriate allowances for defence witnesses.”

With files from The Associated Press