In a statement issued early Wednesday, Harper calls the use of riot police against peaceful protesters in the capital Kyiv "undemocratic and excessive."
His comments came as demonstrators faced off with thousands of riot police in Kyiv's central square Wednesday after an overnight confrontation in which several people were injured.
The protests began late last month when President Viktor Yanukovych backed away from a pact that would deepen the former Soviet republic's economic ties with the European Union.
Harper says Canada and the international community expect Ukrainian authorities to respect and protect the rights of its citizens, including the right to express their opinions freely.
Harper, who was in Pretoria, South Africa Wednesday to view the body of former president Nelson Mandela, also warned that Canada and "like-minded allies" will monitor developments closely and consider all options at their disposal.
“Canada stands with the Ukrainian people during this difficult time and will continue to forcefully oppose all efforts to repress their rights and freedoms," said Harper in the statement.
Squadrons of police in helmets and bearing metal shields converged about 1 a.m. local time on Independence Square, where anti-government protesters have been gathering around the clock to demand the resignation of the government.
Thousands of protesters, their ranks swelling through the night, put up fierce resistance for hours, shoved back at police lines to keep them away from key sites at a camp set up in the square.
Although several demonstrators and police were injured, police appeared to be under orders to refrain from using excessive force, unlike the violent beatings of protesters in recent weeks. Some police officers helped injured activists up from the ground and moved them away.
At dawn, some seven hours after the police siege began, police stood almost motionless while speakers from the protest stage denounced the government and tried to raise demonstrators' spirits.
_ With files from The Associated Press.
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