Monday's violence was the latest high-casualty assault on Afghan forces, who experts say are continuing to suffer "unsustainable" losses since NATO withdrew combat forces from the country in 2014.

Militants detonated a Humvee filled with explosions before three gunmen opened fire at a National Directorate of Security (NDS) intelligence agency base in central Wardak province, but further details have been difficult to independently verify.

A local official told AFP at least 65 people had been killed. The NDS has given a lower toll, instead claiming 36 had been killed and 58 wounded.

Afghan authorities are known to downplay casualties.

The agency said an aerial bombardment in the provincial capital the following night killed eight Taliban insurgents, including the planner of the Monday attack.

"Commander Noman... was killed along with seven other terrorists in an airstrike in Maidan Shar city", it said in a statement.

"NDS will follow the remaining members of this terrorist network and eliminate them all," it added.

The Taliban dismissed the statement as "propaganda" without providing further details.

Wardak provinical council chief Akhtar Mohammad Tahiri said an aerial bombardment did take place in Maidan Shar on Tuesday, but he said it killed four civilians and happened during the day.

The Wardak attack followed a flurry of diplomatic activity by the United States aimed at bringing the Taliban to the table for talks seeking an end to the 17-year war.

Washington on Tuesday confirmed ongoing talks in Qatar between its envoy for Afghanistan Zalmay Khalilzad and representatives of the Taliban.

President Donald Trump has ordered the withdrawal of half of the remaining 14,000 US troops in Afghanistan in a push to extricate Washington from the conflict, launched in 2001 after the September 11 attacks.