At least 430,000 people had been displaced within Ukraine as of yesterday, UNHCR said, 170,000 more than at the start of September.
"With the crisis in Ukraine entering its first winter, UNHCR is racing to help some of the most vulnerable displaced people cope with expected harsh winter conditions," the UN agency said.
"Ongoing fighting in the east, and the resulting breakdown of basic services, continues to drive more people from their homes," it added.
UNHCR said that the need for humanitarian aid was greatest around Donetsk, Kharkiv, Kiev and in the Dnipropetrovsk and Zaporizhia regions.
In addition to those displaced within Ukraine, another 387,000 have fled to Russia, while 6,600 have applied for asylum in the European Union and 581 in Belarus, UNHCR said.
