More than 200 people have been killed in an air strike by Pakistan on a drug rehabilitation facility in Afghanistan's capital, an Afghan official said.

"We lost more than 200 admitted patients here," said Sharafat Zaman, the spokesman for Afghanistan's Health Ministry, about those who were undergoing treatment at the hospital in Kabul.

In a video shared by Kabul-based Hurriyat Radio, Zaman said there were more than 400 casualties who were "innocent civilians and admitted patients (and) there is no military base, and there are no military-related departments or anything else."

Earlier, there were reports of air strikes in Kabul, and the Afghan government accused Pakistan of violating Afghanistan's airspace and bombing the 2,000-bed Omid drug rehabilitation centre.

Islamabad rejected the claims.

Speaking to reporters from the site of the incident, Zaman said "(we) are searching for the injured and admitted patients."

'Fake claim'

His remarks came after Pakistan's Information Ministry rejected Kabul's accusation regarding the attack and said that Islamabad "precisely targeted military installations and terrorist support infrastructure, including technical equipment storage and ammunition storage of the Afghan Taliban and Fitna al-Khawarij in Kabul and Nangarhar (province) that were being used against innocent Pakistani civilians."

"The post-strike detonation of stored ammunition being used by the master terror proxy also fully contradicts the fake claim," it added.

Afghan government spokesperson Zabihullah Mujahid condemned what he called "an act to be against all accepted principles and a crime against humanity."

Relations between Afghanistan and Pakistan have worsened after border tensions escalated last month, causing casualties and property damage.

Since late February, cross-border clashes have killed 107 people on both sides, including 13 soldiers and five civilians in Pakistan, with one soldier still missing.

According to Kabul, 13 soldiers and 76 civilians have been killed in Afghanistan. The figure does not include fresh casualties claimed by Afghan authorities on Monday.

According to UN data, 185 civilian casualties, including 56 deaths from indirect fire and aerial attacks, were reported in Afghanistan between Feb. 26 and March 5.