The UN High Commissioner for Human Rights Navi Pillay Tuesday called on all sides to make greater efforts for a peaceful resolution of the Ukraine crisis.
"Armed opposition groups must stop all illegal actions, including detaining people and seizing public buildings in violation of Ukraine's laws and Constitution," Xinhua quoted Pillay as saying in a statement.
She urged the armed opposition groups to lay down weapons, free "arbitrarily detained persons", and vacate occupied public and administrative buildings.
The UN human rights chief called on the Ukraine government to ensure that military and police operations are undertaken in line with international standards.
"It is extremely important that the authorities themselves demonstrate full respect for the rule of law and scrupulously protect the human rights of all, including the Russian-speaking population," the high commissioner noted.
She urged the authorities to carry out prompt, transparent and comprehensive investigations into the events in Odessa and Donetsk regions that led to the deaths of dozens of people in recent days.
The events included the fire in the trade union building in Odessa Friday last week, which is believed to have killed more than 40 people.