UNITED NATIONS, Feb. 28 (Xinhua) -- The United Nations and partners are preparing to scale up humanitarian operations in Ukraine once the security situation permits, a UN spokesman said on Monday.

Photo taken on Feb. 26, 2022 show a temporary resettlement site for people from Ukraine, in Przemysl, Poland. (Photo: Xinhua)

"Our colleagues are telling us that days of intense clashes across parts of Ukraine have caused civilian casualties and damage to critical infrastructure, with severe humanitarian consequences," he said. "Road damage and insecurity have disrupted local supply chains and access to food and other basic items."

The spokesman said the UN Refugee Agency reported that more than half a million people have already crossed international borders, primarily toward Poland. At least 160,000 were internally displaced.

"Our humanitarian colleagues are also warning that the increasingly intense conflict threatens to trigger a humanitarian catastrophe in Ukraine and in neighboring countries," said Dujarric.

He said the World Food Programme (WFP) is launching a three-month emergency operation in Ukraine to provide food assistance for people fleeing the conflict. The WFP is on standby to assist refugees in neighboring countries, as requested.

WFP teams are on the ground in the Ukrainian capital of Kiev and in a number of neighboring countries, leading the emergency telecommunications and logistics clusters on behalf of the UN's humanitarian community, he said.

The WFP also warns that the Black Sea basin is one of the world's most important areas for grain and agricultural production and that the conflict's impact on food security will likely be felt beyond Ukraine's borders, Dujarric said.