US soldiers

Three other service members were hurt, the Nato alliance said. The explosion occurred near Bagram air base, 50km (31 miles) north of the capital Kabul.

Earlier three people were killed in twin explosions in the eastern city of Jalalabad.

A total of seven US military members have died in Afghanistan in 2019. In March, two soldiers were killed.

The US has about 14,000 troops in Afghanistan.

In February, the top US envoy seeking to broker peace in Afghanistan met the Taliban's co-founder in an attempt to end the 17-year conflict.

A spokesman for the governor in Nangahar province said an Afghan commando had opened fire on the US troops during a joint operation in Achin. He was shot dead in return fire.

Another US soldier was reportedly wounded in the attack.

A spokesman for the Taliban said it had carried out the attack.

Islamic State militants also operate in the area.

Earlier, at least two Afghan policemen were killed by US forces in a so-called friendly fire incident in southern Afghanistan.