GENEVA -- The U.N.'s humanitarian aid and refugee agencies said Wednesday they are seeking $5.6 billion to help millions of people in Ukraine and countries that have taken in fleeing Ukrainians in the wake of Russia's invasion of their country nearly a year ago.

The bulk of the joint appeal -- $3.9 billion -- is for the Office for the Coordination of Humanitarian Affairs, which aims to help more than 11 million people by funneling funds through more than 650 partner organizations.

Refugee agency UNHCR, meanwhile, is seeking $1.7 billion to help some 4.2 million refugees who have fled to 10 host countries in eastern and central Europe.

The joint appeal, one of the largest of its kind for a single country, could draw a large outpouring of funds from Western countries, as a similar appeal did since the war began. Such U.N. appeals rarely get fully funded.

"We were relatively well-funded last year," said Filippo Grandi, the U.N. High Commissioner for Refugees. "I think the refugee appeal was funded in excess of 70% -- not total, but quite good. We count on that to last."

The appeal comes as a string of crises around the world have stretched the generosity of wealthy donors.

"Of course, this is not the only crisis in the world," Grandi added. "There's many others that deserve -- I'm just back from Ethiopia, Burundi. Who talks about Burundi? Sorry, but this is the reality and people need support as much as anywhere else."

The appeal from UNHCR does not cover Russia. Its figures, which are largely drawn from numbers provided by national governments, show that more than 2.8 million refugees from Ukraine have been taken in by Russia.

Grandi said Russia gets funds for those refugees "from other sources" -- including un-earmarked funds.

"We stand ready to do more if it's needed for any Ukrainian that is in need in Russia," he said. "That offer is on the table and is available."

The U.N. says humanitarian groups helped nearly 16 million people in Ukraine last year, including in areas not controlled by the Kyiv government. More than one-third of those received cash assistance, which can help prop up the battered national economy.