"We live in a period of unprecedented mobility with 250 million international migrants and 750 million internal migrants," IOM director general William Lacy Swing said ahead of a migration conference in Bangkok on Friday.
"We are also seeing the highest number of forced migrants since the Second World War," Swing said, attributing the high numbers to the Ebola outbreak last year, ethnic clashes in sub-Saharan Africa and ongoing political instability in the Middle East.
Swing said there had been a backlash against migration after the Paris terrorist attacks last month, carried out by Islamic extremists who had reportedly travelled freely between Europe and the Middle East.
"There is growing anti-migrant sentiment but governments have forgotten that historically migration has been a net positive," he said.
The conference on Friday will likely touch on the issue of Rohingya refugees, ethnic Muslims from Myanmar who face persecution, and the crisis that left thousands of them stranded at sea earlier this year.