Prime Minister Stephen Harper made pointed references to Ukraine's current and past political struggles as he spoke to a team of Canadian election observers set to monitor elections in the eastern European nation.

Harper told the observers, many of whom are Ukrainian-Canadian, the mission is important because of Canada's close ties with the country through more than a century of immigration and because of the importance of ensuring Ukraine continues on a democratic path.

"This election is pivotal for Ukraine," Harper said.

He recalled his own visit to Ukraine two years ago and his visit to a museum in a former Communist-era prison where Ukrainians were detained and tortured by Stalin's secret police. He said the museum's own director — who was present at the send-off event in Gatineau, Que., on Friday — had been harassed by Ukraine's modern-day "secret police."

"Friends, in such rights abuses as these, we see how the darker side of Ukraine's history threatens its future," Harper said.

Harper made reference to the trial of Yulia Tymoshenko, the former prime minister who lost a presidential run-off in 2010 to the current pro-Russian president, Viktor Yanukovych.

She remains in prison, the prime minister said, as "do many others who have fallen afoul of the Ukrainian government."

"As our own all-party parliamentary committee recently concluded, and I quote: 'There is serious cause for concern about Ukraine’s democratic development and respect for the rule of law,'" Harper said.

"We continue to call upon President Yanukovych to respect judicial independence, to cease the harassment of opposition voices and to conduct an election that is indeed free and fair," Harper said.

Harper also announced the mission will be headed by Raynell Andreychuk, a Conservative senator from Saskatchewan. Andreychuk, a former judge and ambassador, has served as a representative to the United Nations.

This is the fifth time Canada has sent election observers to Ukraine.