Detained immigrants, who fail to provide legal documents, are transported by police in a bus for shifting to a deportation center in Karachi, Pakistan, Nov 2, 2023. (PHOTO / AP)

KABUL/PESHAWAR – Pakistan's northwestern border crossing was flooded with thousands of people looking to cross into Afghanistan on Thursday, a day after the government's deadline expired for undocumented foreigners to leave or face expulsion.

The Afghan caretaker government has, meanwhile, announced building shelters for the stream of refugees returning from Pakistan, the state-run Bakhtar news agency reported.

Pakistani authorities had begun rounding up undocumented foreigners, most of them Afghans, hours before the deadline. More than a million Afghans could have to leave Pakistan or face arrest and forcible expulsion as a result of the directive that Islamabad delivered abruptly a month ago.

READ MORE: Afghans head back home as Pakistan moves to expel 1.7m

The Pakistan government said Afghans had been involved in militant attacks and crime in the country and has brushed off calls from the United Nations, rights groups and Western embassies to reconsider its expulsion plan.

Of the more than 4 million Afghans living in Pakistan, the government estimates 1.7 million are undocumented

More than 24,000 Afghans crossed into Afghanistan using the Torkham border crossing on Wednesday alone, Deputy Commissioner Khyber Tribal District Abdul Nasir Khan told Reuters.

"There were a large number waiting for clearance and we made extra arrangements to better facilitate the clearance process," he said.

Khan said authorities had worked well into the night at a camp set up near the crossing. The border is usually closed by sundown.

He said 128,000 Afghan nationals have left for Afghanistan through the border crossing since the Pakistan government gave its ultimatum, and thousands more are expected to cross in coming days.

Pakistan authorities have barred media access to the border crossing since Tuesday.

Some Afghans who have been ordered to leave have spent decades in Pakistan, while some have never been to Afghanistan, and wondering how they can start a new life there.

A police officer conducts biometric identification of a resident during a search operation against illegal immigrants, at a neighborhood of Karachi, Pakistan, Nov 2, 2023. (PHOTO / AP)

Of the more than 4 million Afghans living in Pakistan, the government estimates 1.7 million are undocumented.

Many fled during the decades of conflict that Afghanistan suffered since the late 1970s, while another exodus took place after the Taliban takeover in 2021.

ALSO READ: Afghans among 140,000 leaving Pakistan as deadline set to expire

Before the deadline, 140,322 foreigners had already left Pakistan voluntarily, according to officials, and major roads leading to border crossings into Afghanistan have been jammed with trucks carrying families and whatever belongings they could carry.

In this Nov 1, 2023 photo, Afghans wait for clearance to depart for their homeland at a deportation camp setup by authorities to facilitate people living in Pakistan illegally, in Chaman, a town on the Pakistan-Afghanistan border. (PHOTO / AP)

Afghan shelters

Afghanistan’s Acting Minister for Refugees and Repatriation Khalil Rahman Haqqani instructed the construction of shelters for returning Afghans during his recent visit to the Torkham crossing point which borders Pakistan, according to a Bakhtar agency report.

More than 150,000 Afghan refugees returned home from Pakistan via Torkham over the past few days, the report said.

Over the past month, more than 200,000 Afghan refugees, with the majority of them via Torkham border town and some via Spin Boldam and other crossing points, have reportedly returned to their homeland.

Zabihullah Mujahid, chief spokesman for the Afghan caretaker government, said in a message posted on X, formerly Twitter, that authorities in Torkham were preparing 10,000 lunches and 30,000 dinners for the returnees on Thursday.