"Ahead of World Refugee Day, we have to be aware of our responsibility to treat refugees and migrants humanely," said Michael Georg Link, head of the OSCE's Office for Democratic Institutions and Human Rights.
"States should continue to work to ensure that the human rights of all individuals -- including refugees and other migrants -- are respected within their countries, as well as to find ways to prevent discrimination against these vulnerable groups."
Recent events "have raised the question of the treatment of refugees to the top of policy agendas," he was quoted in a statement as saying in Hungary, where the government this week announced plans to erect a fence along its border with Serbia to keep out migrants.
Saturday's World Refugee Day comes as Europe struggles to cope with a flood of migrants and refugees arriving from Syria, Iraq, Afghanistan and elsewhere, many crossing the Mediterranean in ramshackle boats to Italy and Greece.
The journey is perilous, with the UN's refugee agency saying on Thursday that it has received information of more than 3,500 women, men and children reported dead or missing in the Mediterranean Sea during 2014.
On Tuesday, EU interior ministers failed to agree on European Commission proposals to redistribute 40,000 Syrians and Eritreans in Europe and to resettle 20,000 Syrians living in camps outside the bloc.