A major escalation following months of cross-border violence has seen deadly fighting along the frontier and multiple Pakistani strikes on Afghanistan since Thursday.

Construction worker Noor Agha, 21, said he was busy tiling "when the Pakistani planes attacked" the site near Takhta Pul village on Saturday.

"They bombarded the sheds, then we went inside the mountain," he told AFP, with hills visible in the distance. "Some people were martyred, two or three were wounded."

The head of the facility gave a figure of three killed and seven wounded.

Agha said two strikes hit the site, where a destroyed car sat in front of a building covered in shrapnel marks.

The Pakistani military did not respond to an AFP request to comment on the incident.

Construction was underway to support Afghan returnees from Pakistan and Iran, local officials said.

Around 5.4 million Afghans have entered the country from the two neighbours since late 2023, according to UN figures, largely the result of pushbacks by Tehran and Islamabad.

Bahawaldin Nazim, the head of the facility, said it was "being built for returned migrants" and there was "no military site" there.

"Labourers travelling from Khost, Kabul and other areas were killed."

- 'Everything went dark' -

Jobs are scarce in Afghanistan, which is suffering from an economic crisis compounded by aid cuts, banking restrictions, and the mass returns.

Rahimullah, a labourer who only gave one name, said he had sent his son to get generator fuel when the first strike hit.

His other son called on his brother to return, and the family "wanted to escape from the area, but then there was another air strike", said the 52-year-old.

The Afghan government said Pakistani fire has killed more than 30 civilians since Thursday.

Casualty claims from both sides are difficult to verify independently.

In Takhta Pul, Rahimullah's 20-year-old son Enamullah said "everything went dark before our eyes" after the second strike.

"We didn't understand anything," he said, with blood stains on his tattered shirt and plasters on his face.

"I came from Kabul just to earn a piece of bread," the construction worker told AFP.

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