UNITED NATIONS (Reuters) - United Nations Secretary-General Antonio Guterres spoke with Ukraine's President Volodymyr Zelenskiy on Saturday, telling him the world body plans to "enhance humanitarian assistance to the people of Ukraine", a U.N. spokesperson said.

       "He informed the President that the United Nations would launch on Tuesday an appeal to fund our humanitarian operations in Ukraine," the U.N. spokesperson said in a statement.

       U.N. aid chief Martin Griffiths said on Friday that more than $1 billion will be needed for aid operations in Ukraine over the next three months as hundreds of thousands of people are on the move after Russia invaded its neighbor.

       (Reporting by Michelle Nichols; Editing by Cynthia Osterman)