Blast, gunfire heard near Interior Ministry in Kabul: Police

It was not clear if there had been any casualties and no group immediately claimed responsibility for the attack.

"We can confirm an explosion and gunfire at the first checkpoint of the interior ministry building. Security forces are there to assess the situation," interior ministry spokesman Najib Danish told AFP, in a statement echoed by police.

Both the Taliban and the Islamic State group have stepped up their attacks on Kabul, making the capital the deadliest place in the country for civilians in recent months.

Last week the Taliban called on Kabul residents to "keep away" from military and intelligence centres in the heavily fortified city, saying they plan more assaults as part of their annual spring offensive.

"Therefore, to avoid civilian casualties and only cause damage to enemy military, we are asking Kabul residents to keep away... we don't want even a single innocent civilian to be killed," said a statement published online.

In response, the defence ministry said police and troops are "ready to protect the people with all means possible", and would not allow the militants to reach their "un-Islamic and inhuman goals".

The Taliban did not define what was meant by "military and intelligence centres".

Such targets are difficult to avoid given that the overcrowded city is the heart of the country's intelligence, government and military operations and plagued by traffic jams due to ubiquitous checkpoints and barriers.

Kabul accounted for 16 percent of all civilian casualties last year, when 1,831 civilians were killed or wounded nationwide, according to the United Nations Assistance Mission in Afghanistan.

The UN has warned that 2018 could be even deadlier.