By Asad Hashim
ISLAMABAD (Reuters) - More than five times the number of Afghan refugees returned home from Pakistan in August than in July, the United Nations' refugee office said on Tuesday, seeking to escape harassment in the host nation and stiffer measures on visits home.
Pakistan is home to the world's second-largest refugee population, including 2.5 million Afghans, many living there since the Soviet Union invaded Afghanistan in 1979.
Until recently the Afghan refugees did not need passports or visas to cross the porous border and visit families left behind.
But Islamabad has begun asking for such documents following brief cross-border clashes in June between Afghan and Pakistani forces that killed four people at the main Torkham crossing on the disputed 2,600-km (1,616-mile) -long frontier.
The U.N. High Commission for Refugees said 67,057 refugees were permanently repatriated in August, up from 12,962 the month before and 1,250 in June.
"The main reason for this is the closing of the Torkham border gate, because these people want to be able to go back and forth across the border, and that has completely stopped," said Baryali Miankhel, president of the Supreme Council of Afghan Refugees in Pakistan's Khyber Pakhtunkhwa province.
Torkham is 180 km (112 miles) northwest of Pakistan's capital of Islamabad and 170 km (106 miles) east of Kabul, the Afghan capital.
"These people have brothers and other relatives on the other side, that's why the border restrictions are the main reason," Miankhel added.
Under the UNHCR program, refugees returning home get a special document permitting them to make the journey.
In June, Pakistan extended Afghan refugees' right to stay until December 2016, but restrictions and harassment have grown, say refugees and the UNHCR. [nL4N19L3QP]
"The increase in the number of security operations against undocumented foreigners has also impacted refugees' decision-making," said UNHCR spokeswoman Duniya Aslam Khan.
Police increasingly demand bribes from refugees, Miankhel said, even those with Proof of Registration cards showing a legal right to stay.
"The police harass people, ask for money, and confiscate refugees' cards unless they are paid bribes," he added.
Pakistani authorities deny harassing Afghan refugees.
Repatriations are on course this year to reach their highest level since 2008, with the UNHCR saying 103,013 refugees have returned to Afghanistan from Pakistan, 93 percent within the last two months.
The surge coincided with a doubling of the UNHCR's grant for returning refugees, to $400, Khan said.
"There is increasing anxiety among the Afghan refugees regarding what will happen when Proof of Registration cards expire in December 2016," said Khan.
(Writing by Asad Hashim; Editing by Drazen Jorgic and Clarence Fernandez)