KABUL: Militants attacked an international charity in Kabul Tuesday during an hours-long assault labelled a “war crime” by Amnesty, as the capital reeled from a wave of violence that killed at least 41 and wounded dozens.

The assault on CARE International began late Monday with a massive car bombing, just hours after the Taliban carried out a brazen double bombing near the defence ministry.

A plume of smoke rose over the upscale neighbourhood of Shar-e Naw after the raid on the charity, located next to the office of Afghanistan's former intelligence chief Rahmatullah Nabil.

It remains unclear which compound was the intended target of the attack, which left piles of rubble and shards of glass strewn across the area.

“An armed group launched an attack on what is believed to have been an Afghan government compound located close to the Kabul office of CARE,” the charity said, adding its staff had been safely evacuated.

“The incident continued through early Tuesday morning with damages sustained to the CARE compound.”

The interior ministry said 42 people including 10 foreigners were rescued.

It added that six people had been wounded in the attack, which ended Tuesday morning when Afghan forces gunned down all three attackers.

No militant group has so far claimed responsibility for the raid on the charity, but it comes as the Taliban ramp up their nationwide offensive against the US-backed government.

The attack on CARE International “is the deliberate targeting of civilians and constitutes a war crime”, Amnesty International said, calling for an independent probe to bring the perpetrators to justice.

The assault had been preceded by twin Taliban blasts that killed at least 41 people during rush hour on Monday, including high-level officials, and left 110 wounded.

The rise in casualties was announced on Tuesday by the health ministry, which had earlier put the death toll at 24 with 91 wounded.

The second of the two explosions struck just as soldiers, policemen and civilians hurried to help the victims of the first blast.

Double tragedy

High-level defence officials were among those killed, including a young military officer. Compounding the tragedy, his mother also died when she heard of his death.

“Colonel Ahmed's mother died of a heart attack after hearing of her son's martyrdom,” former deputy interior minister Ayub Salangi tweeted.

“She lost two other sons before him.”

Ambulances were overwhelmed by the carnage outside the defence ministry Monday. There were so many disfigured bodies that some had to be taken to hospitals in car boots and the back of police trucks.

Firemen raced to retrieve some bodies thrown into the Kabul River by the force of the blast.

The violence, condemned by President Ashraf Ghani, came more than a week after 16 people were killed when militants stormed the American University in Kabul.

Earlier in August two professors from the university, an American and an Australian, were kidnapped at gunpoint near the campus. Their whereabouts are still unknown and no group has publicly claimed responsibility for the abductions.

The uptick in violence in the capital comes as the Taliban escalate nationwide attacks, underscoring the worsening security situation and the heavy price paid by civilians since NATO forces ended their combat mission at the end of 2014.

Afghan forces backed by US troops are trying to head off a potential Taliban takeover of Lashkar Gah, the capital of the southern opium-rich province of Helmand.

The Taliban have also recently closed in on Kunduz -- the northern city they briefly seized last year in their biggest military victory since the 2001 US invasion -- leaving Afghan forces stretched on multiple fronts.