Pakistan on Wednesday gave 1.6 million Afghan refugees the right to stay another six months, extending a deadline on their residency papers that had been due to expire at the end of December.

The decision was taken by Prime Minister Raja Pervez Ashraf, according to a statement from his office. His spokesman confirmed that Afghan refugees would now be entitled to stay in Pakistan until the end of June 2013.

A spokeswoman for the UN Refugee Agency said Pakistan had promised not to expel any registered refugee.

"We got assurances from Pakistan that they would respect the voluntary nature of returns and would not expel any registered refugee," Duniya Aslam Khan told AFP.

More than five million Afghans fled their homeland for Pakistan in the early 1980s, soon after Soviet troops invaded Afghanistan.

Since the 2001 US-led invasion brought down the Taliban, 3.8 million have returned, leaving 1.6 million behind, most born and brought up in Pakistan.

In late October, UNHCR boosted incentives for Afghans to return and around 10,000 Afghans went home from October 23 to November 30 -- more than double the number who were repatriated in the same period last year.

But despite pressure from Islamabad and the extra incentives, the vast majority of the Afghans still in Pakistan are reluctant to return to a country gripped by war and poverty