At least 13,000 migrants along Turkish-Greek border: UN

Some 13,000 migrants have gathered along the Turkish-Greek border after Turkey's president threatened to allow some of the some 3.6m refugees in the country cross into Europe, the UN said.

"Thousands of migrants, including families with young children, are passing a cold night along the border between Turkey and Greece," the International Organization for Migration said in a statement. The UN agency said its staff had been tracking the movement of people from Istanbul and were providing humanitarian assistance to the most vulnerable.

"By Saturday evening, staff working along the 212kilometre-long border between Turkey and Greece and in the capital had observed at least 13,000 people gathered at the formal border crossing points at Pazarkule and Ipsala and multiple informal border crossings," it said. The agency said it had spotted "groups of between several dozen and more than 3,000.

"The number of migrants moving through Edirne towards the border grew through the day as cars, taxis and buses arrived from Istanbul," the head of IOM's Turkey mission Lado Gvilava said in the statement. Gvilava said the IOM was distributing food and other basic supplies, but with temperatures dropping close to freezing "we're concerned about these vulnerable people who are exposed to the elements."

The mass movement of people began after Turkey's President Recep Tayyip Erdogan threatened to open the gates and allow refugees to travel to Europe as a way to pressure EU govts over the Syrian conflict. Joe Biden won the South Carolina primary, reviving his flagging campaign and positioning himself as the leading rival to frontrunner Bernie Sanders in race for the Democratic presidential nomination.