More than 350,000 Afghan refugees have returned to their war-torn homeland from Pakistan this year, UN data show, with the torrent of people crossing the border expected to continue.

Earlier in October the UN’s refugee agency UNHCR said the number of documented Afghan refugees returning had soared past 200,000.

But this week the body’s Office for the Coordination of Humanitarian Affairs (OCHA) in Afghanistan released updated figures that also include the number of undocumented refugees crossing the border.

“So far this year, 162,186 undocumented returnees and 207,236 registered returnees (369,422) have returned to Afghanistan from Pakistan,” an OCHA statement said, noting that the majority, some 333,000 people, have returned since July.

“If that sounds like a lot, it is,” the statement continued.

“Based on current trends, we expect a further 446,000 (both registered and undocumented) Afghans to arrive before year-end.”

The influx of refugees threatens to overwhelm Afghanistan, with authorities there already warning of a humanitarian crisis as hundreds of thousands of people flee fighting within the country.

“Due to hostilities in Kunduz and intensified fighting across the south we have seen a jump of 37,000 IDPs (internally displaced people) alone — more than 10 per cent of the year total in just one week,” Danielle Moylan, a spokeswoman for OCHA, told AFP on Monday.

The total number of IDPs due to fighting since the start of the year stands at 323,500.

Pakistan hosts 1.4 million registered Afghan refugees, according to UNHCR figures from earlier this year, making it the third-largest refugee hosting nation in the world. A further one million unregistered refugees are estimated to be in the country.

OCHA said that the vast majority of undocumented returnees claim they intend to return to the eastern province of Nangarhar. Many also settle in Kabul.