Afghanistan accused Pakistan on Tuesday of hitting a treatment centre for drug addicts in its capital, though Islamabad denied deliberately targeting civilians.

The Afghan health ministry said that about 400 people were killed and more than 200 wounded, but that the toll was not final as rescue operations are ongoing.

The Pakistani military has struck Kabul several times in recent weeks, as part of a conflict sparked by claims that the Taliban government has harboured extremists who have carried out attacks across the border.

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

Pakistan is one of China's closest partners in the region, but Beijing also calls itself a "friendly neighbour" of Afghanistan.

A Chinese special envoy spent a week mediating between the two countries, according to Beijing's foreign ministry.

"China... will continue to leverage its own channels to play a constructive role in de-escalating tensions and facilitating the improvement of bilateral relations," spokesman Lin Jian told reporters on Tuesday.

"Dialogue and negotiation constitute the only effective means of resolving issues between the two countries."