(AFP) - Hundreds of thousands of Afghans living in Pakistan faced detention and deportation on Wednesday, as a government deadline for them to leave sparked a mass exodus.

The government has given 1.7 million Afghans it says are living illegally in the country until November 1 to leave voluntarily or be forcibly removed.

Thousands joined a snaking queue that stretched seven kilometres (four miles) at the busiest border point on Wednesday, with border officials reporting at least 29,000 people crossed into Afghanistan the day before.

"Since November 1, the process of arrest and subsequent deportation of illegal foreigners has begun. However, the voluntary return of illegal foreigners will also continue and be encouraged," the interior ministry said in a statement.

It said more than 140,000 people have left Pakistan since the start of October when the order was issued by an unelected caretaker government ahead of elections due in January.

Forty-nine holding centres, some capable of holding several thousand people, opened across the country on Wednesday to process and deport Afghans, state media said.

"My heart doesn't really want to return to Afghanistan but I have no other choice," said 32-year-old Irfanullah, as he waited to be deported.

"The police were harassing me... they used to disrespect all the men and women by entering our houses, that's why we are returning, to avoid further humiliation."

Millions of Afghans have poured into Pakistan in recent decades, fleeing a series of violent conflicts, including an estimated 600,000 since the Taliban government seized power in August 2021 and imposed its harsh interpretation of Islamic law.

Human Rights Watch has said Afghans awaiting resettlement to the United States, United Kingdom, Germany and Canada after fleeing the Taliban government are at risk of deportation after their Pakistan visas expired.

Pakistan has said the deportations are to protect its "welfare and security" after a sharp rise in attacks, which the government blames on militants operating from Afghanistan.

- 'Emergency situation' -

Authorities on the Afghan side of the border have been overwhelmed by the scale of the exodus as they attempt to process those returning -- some of whom are setting foot in Afghanistan for the first time in their lives.

Samiullah Samoon, who leads immigration registration at Torkham, said the crossing is facing "an emergency situation".

After fleeing to Afghanistan, 35-year-old Benafsha, four months pregnant with her seventh child, was waiting to be processed before moving on to her province of origin, Kunduz, with her family.

"In Kunduz, we don't have land, or a home, or work," said the woman, who was never documented in Pakistan despite living there almost all her life.

"We don't have anything there."

The Taliban government has urged Pakistan to give undocumented Afghans in the country more time to leave as pressure mounts at border posts.

- 'Enough is enough' -

Lawyers and rights groups have accused the Pakistani government of using threats, abuse, and detention to coerce Afghan asylum seekers to leave while Afghans have reported weeks of arbitrary arrests and extortion.

"The constitution of Pakistan gives every person who is present on this soil right to a fair trial but these refugees have been denied that right," said Moniza Kakar, a Karachi-based human rights lawyer.

The expulsion of undocumented Afghans, however, has widespread support from Pakistanis, analysts say, with a protracted refugee presence putting a heavy burden on the country's infrastructure.

Thousands of families arrived voluntarily on Wednesday at a holding centre in Landi Kotal near the Torkham border, in Khyber Pakhtunkhwa province, where the majority of Afghan migrants live.

In other cities, Police vans with detained Afghans were seen arriving at urban holding centres.

Authorities have also targeted houses and businesses they deem illegal, as well as Pakistanis accused of sheltering undocumented Afghans.

"Enough is enough, tell us the route and we will arrange a vehicle and leave today. This humiliation is too much," said 35-year-old Baaz Muhammad, who was born in Pakistan to refugee parents, as he watched a bulldozer raze his home.

In Balochistan, the government said it was going door-to-door to trace undocumented Afghans who had refused to leave before the deadline.

A 14-year-old Afghan girl, whom AFP has not identified for security reasons, said she would stay in Pakistan as long as possible, despite not having legal papers.

"We are not going back home, because my education in Afghanistan would come to a grinding halt," she told AFP in Peshawar.

"Our father has told us that if he is arrested by Pakistani authorities, we should not leave even then. Because we will have no life in Afghanistan."

© Agence France-Presse