At least 19 people have been killed and 43 injured in a powerful explosion in the Afghan capital Kabul on Tuesday according to a source in the interior ministry.

Earlier, a witness said the blast was followed by the sound of gunfire heard close to the Sardar Mohammad Daud Khan military hospital.

It was not immediately clear whether there were any casualties or what had caused the explosion and no comment was immediately available from Taliban officials.

Bilal Karimi, a senior Taliban official, told Tolo News that "two explosions occurred in Kabul city's district 10", while the city's former and current residents also shared images and testimonies from the site of the incident.

"A suicide attacker detonated his explosives outside of Wazir Akbar Khan hospital close to the military hospital. A number of attackers fighting in the area. A number of casualties and fatalities," tweeted Toronto-based Afghan journalist Bilal Sarwary, quoting a doctor and witness.

Islamic State, which has carried out a series of attacks on mosques and other targets since the Taliban's seizure of Kabul in August, attacked the 400-bed hospital in 2017, killing more than 30 people.

This is a developing story.