WATCH: Chaos as 'thousands of stranded Afghans' pour across Pakistan border amid coronavirus pandemic

The footage, which cannot be independently verified, shows thousands of people rushing through the Torkham checkpoint without showing any documentation.

On Saturday, Pakistan announced it would open its border with Afghanistan for four days to allow stranded Afghan citizens, who hail from the Pashtun ethnic group, to return home, after the coronavirus pandemic prompted its closure.

While authorities said they would allow 1,000 people a day, according to the UN's International Organization for Migration (IOM), at least 60,000 crossed into Afghanistan in three days.

Arrangements to quarantine the expected influx were futile, as authorities from the nearby Afghan province of Nangahar were quickly overwhelmed by the numbers, according to local reports.

Pakistan is one of the South Asia countries worst affected by the novel coronavirus, recording a total of 4601 confirmed cases and 66 deaths.

Afghanistan on the other hand, remains less hard hit, reported only 423 cases and 14 deaths.

The development now raises fears that the flow of the mostly impoverished returnees through the country's porous eastern border could lead to a devastating surge in rates of transmission.

Yet concerns are even greater surrounding the impact of the spontaneous entry of over 150,000 Afghans across the country’s opposite border with Iran, the Middle East epicentre of the virus.

Read more: Thousands of Afghans flee 'coronavirus epicentre' in Iran, prompting fears of catastrophic outbreak

Most Iranian returnees are still untested and unmonitored. Neither governmental nor independent agencies with the capacity to test or quarantine were present at the border during the month of March, when movement peaked.

The key difference between the influx of Afghans from Pakistan and those from Iran is that he former had been in the neighbouring country for short-term work, study or to receive medical treatment, while the latter are settled refugees, according to Sebghatullah Saber, Afghan correspondent for The New Arab’s Arabic language service.

Closures of businesses, including factories and construction companies, have destroyed livelihood for Iran's Afghan minority, who are mostly members of the Hazara ethnic group.

Despite Iranian Foreign Minister Jawad Zarif assuring Afghan President Ashraf Ghani that Afghan refugees would receive health services in the wake of the pandemic, fears of being turned away from treatment have driven the masses back to their war-torn homeland.

Afghanistan imposed a lockdown in Kabul and Herat province, which neighbours Iran, on 28 March.

The government's response has been hobbled by continuing violence and a political crisis, with two candidates claiming to have won recent presidential elections.

Follow us on Facebook, Twitter and Instagram to stay connected