PRAGUE (Reuters) - The situation in Ukraine remains dire and the number of refugees fleeing the Russian invasion couldl potentially rise to 1.5 million by the end of the weekend from a current 1.3 million, the head of the U.N. refugee agency said on Saturday.

       "This is the fastest moving refugee crisis we have seen in Europe since the end of World War Two," UNHCR head Filippo Grandi told Reuters in a telephone interview.

       Grandi also said most refugees at the moment were linking up with friends, family and other connections already living in Europe, but warned future waves would be more complex.

       (Reporting by Michael Kahn and Jason Hovet; Editing by Frances Kerry)