More than 50 million people were forcibly uprooted worldwide at the end of last year, the highest level since after World War Two, as people fled crises from Syria to South Sudan, the UN refugee agency said.

Half are children, many of them caught up in conflicts or persecution that world powers have been unable to prevent or end, UNHCR said in its annual Global Trends report on Friday.

"We are really facing a quantum leap, an enormous increase of forced displacement in our world," Reuters cited UN High Commissioner for Refugees Antonio Guterres telling a news briefing.

The overall figure of 51.2 million displaced people soared by six million from a year earlier. They included 16.7 million refugees and 33.3 million displaced within their homelands, and 1.2 million asylum seekers whose applications were pending.