The U.N. refugee agency is expressing concerns that migrants and refugees who have been moved to several sites with "sub-standard conditions" after being evacuated from a makeshift camp near Greece's border town of Idomeni.

UNHCR says some evacuees were taken to "derelict warehouses and factories" with "insufficient" supplies of food, water, toilets, showers and electricity.

At a briefing in Geneva on Friday, UNHCR spokeswoman Melissa Fleming called on Greek authorities, with financial support from the European Union, to find "better alternatives quickly" for some of those moved out from Idomeni, which is near the Macedonian border.

The agency said in a statement Friday that it was concerned that some families are being separated during their transfer from Idomeni, but noted that the evacuations took place "without the use of force."