Prime Minister Stephen Harper, at an award reception in Toronto, reinforced Canada's opposition to the prison sentence given to a Ukrainian opposition leader.

Harper said he was "deeply concerned" by the case of Yulia Tymoshenko during a speech Friday to the Ukrainian Canadian Congress where he received the Shevchenko medal, the organization's highest award.

Tymoshenko, a former prime minister of Ukraine and a driving force behind the country's 2004 pro-democracy Orange Revolution, was sentenced to seven years in prison on charges of abuse of power over a gas deal she signed with Russia in 2009.

"The conduct of Tymoshenko's trial does not reflect accepted norms of due process or fairness," Harper said in a speech that was released to the media ahead of the event.

Harper also sent a letter to Ukrainian President Viktor Yanukovych saying the trial appeared to be politically motivated.

During his speech, Harper warned the ruling, which included a three-year ban from government posts and a 1.5 billion hryvna ($196 million Cdn) fine for Tymoshenko, "may have serious consequences for [the countries'] bilateral relationship."

Ruling also condemned by EU, Russia

Foreign Affairs Minister John Baird said Tuesday that Canada was troubled by the prison sentence.

"The apparent political bias and arbitrary prosecution in this and other cases hamper Ukraine's democratic development," he said in a release. "A legitimate and active opposition is a vital part of a vibrant and effective democracy."

The European Union and Amnesty International also condemned the ruling. Russian Prime Minister Vladimir Putin, meanwhile, said the 2009 deal conformed with Russian and Ukrainian law.

Some have said the sentence was designed to eliminate one of Yanukovych's political rivals in advance of Ukrainian elections next year.

Tymoshenko has said she would contest the ruling in the European Court of Human Rights and her lawyers said they would appeal the verdict in local courts.

Some analysts believe Tuesday's decision could still be reversed, giving Tymoshenko the chance to walk free.

With files from The Associated Press