India, July 1 -- More than 700,000 Afghan migrants have returned from Iran so far this year, including 256,000 in June alone, the UN International Organization for Migration (IOM) reported on Monday, warning of immense pressures on Afghanistan's overstretched support systems.

Ninety-nine per cent of the returnees were undocumented, and 70 per cent were forcibly returned, with a steep rise in families being deported - a shift from earlier months, when most returnees were single young men, according to the UN agency.

The rise follows a March decision by the Iranian Government requiring all undocumented Afghans to leave the country.

"They are coming in buses and sometimes five buses arrive at one time with families and others and the peop...