Hundreds more were said to have been wounded at the facility, which was hit Monday night, flattening buildings used to treat people from across the country for addictions to marijuana, amphetamines and other narcotics.

There was no immediate independent verification of the toll, but AFP reporters saw at least 30 bodies taken from the site in the chaotic and smouldering aftermath of the attack on Monday night.

They then saw more than 65 removed on Tuesday as rescuers picked through the rubble searching for victims and survivors.

"The toll is not final as the rescue operation is still going on, but we have around 400 martyrs and more than 200 wounded," said health ministry spokesman Sharafat Zaman.

Interior ministry spokesman Abdul Mateen Qani gave a toll of "408 killed and 265 wounded" at the same briefing.

In Geneva, UN rights office spokesman Thameen Al-Kheetan called for a swift, independent investigation into the strike, with those responsible "held to account in line with international standards".

But Pakistan's Information Minister Attaullah Tarar said Taliban government claims that Pakistan deliberately targeted the clinic were "entirely baseless".

"No hospital, no drug rehabilitation centre, and no civilian facility was targeted," he wrote on X.

"The targets were military and terrorist infrastructure, including ammunition and technical equipment storage sites and other installations linked to hostile activity against Pakistan."

Late Tuesday, Afghan Foreign Minister Amir Khan Muttaqi said that Afghanistan does not want war but would continue "proportionate and legitimate defensive measures until the other side ceases its violations".

The two sides have been in conflict for months, with Islamabad accusing its neighbour of harbouring Islamist extremists who have mounted deadly cross-border attacks on its territory.

- Search for survivors -

Chairs, blankets, pieces of hospital beds and human remains could be seen in the blackened ruins of the rehabilitation centre on Tuesday.

Crowds gathered outside as family members sought news of their loved ones while rescuers picked through the rubble nearby.

Habibullah Kabulbai, 55, arrived at the centre on Monday night, hoping to find his brother, Nawroz, who was admitted five days ago.

"I can't find him," he said, weeping. "What should we do? I have no words... We are helpless. This has not only happened to me but the whole of Afghanistan."

Monday evening's attack triggered panic in Kabul, sending people running for cover as anti-aircraft guns fired back not long after they had broken their daily Ramadan fast.

"I heard the sound of the jet patrolling," Omid Stanikzai, 31, a security guard at the drug treatment centre, told AFP.

"There were military units all around us. When these military units fired on the jet, the jet dropped bombs and a fire broke out."

All of the dead and injured were civilians, he added.

Pakistan's Tarar said the six strikes conducted on Monday also hit the eastern border province of Nangarhar, calling them "precise, deliberate, and professional".

- 'De-escalate' -

The EU on Tuesday called for "maximum restraint" from both Afghanistan and Pakistan, describing the strike on the medical facility in Kabul "a new and deadly escalation" of the conflict.

The United Nations mission in Afghanistan (UNAMA) called for an "immediate ceasefire". Between February 26 and Monday before the strike, at least 76 civilians had been killed in Afghanistan due to the hostilities, it added.

Pakistan's arch-foe India called Monday's strike "a cowardly and unconscionable act of violence" that threatened regional peace and stability.

China's foreign ministry urged the two countries to "swiftly implement a ceasefire" and resolve their differences through dialogue.

But South Asia expert Michael Kugelman, from the Atlantic Council international affairs think-tank, said the fighting showed little sign of ending soon, particularly with Gulf states who have previously mediated "bogged down by their own war".

"Pakistan appears intent to keep hitting targets in Afghanistan, and the Taliban determined to retaliate with operations on Pakistani border posts and potentially with asymmetric tactics -- from launching drones to sponsoring militant attacks in wider Pakistan," he told AFP.

"There are no off-ramps in sight."