JALALABAD, Afghanistan: As many as three Afghan civilians were killed early on Monday morning when American troops opened fire after their vehicle struck a roadside bomb, an official in eastern Nangarhar province said.

A man and his two sons were killed at their home in Gani Khel, a district in the south of Nangarhar, on the border with Pakistan, said Attaullah Khogyani, a spokesman for the provincial governor.

“After the bomb blast hit them, the American forces then started shooting and killed one man and two children nearby,” he said.

The US military command in Kabul said it was investigating the reports.

Civilian casualties have running at near record highs as fighting spreads to more areas of Afghanistan, according to the United Nations.

Afghan President Ashraf Gani generally has been less vocal than his predecessor, Hamid Karzai, in publicly criticising the US military when troops are involved in incidents where civilians are killed.

On Saturday, three American soldiers were killed and one wounded when an Afghan soldier opened fire on them in Nangarhar, where elite US troops have been helping Afghan forces battle Daesh militants.

Also over the weekend, an American air strike in southern Afghanistan killed at least three Afghan policemen and wounded several others during a joint operation by Afghan and US special forces.

US and Afghan troops have been battling militants in Nangarhar province for months.

Islamic State, or Daesh, has established a stronghold in the region, which borders Pakistan. US military officials estimate there are about 600 to 800 Daesh fighters in Afghanistan, mostly in Nangarhar, but also in the neighbouring province of Kunar.

The increase in involvement by US troops and warplanes comes as US President Donald Trump’s administration weighs whether to deploy more troops in the war-torn country.

Reuters reported in late April that the US administration was carrying out a review of Afghanistan and there were conversations over whether to send between 3,000 and 5,000 US and coalition troops to Afghanistan.

Deliberations include giving more authority to forces on the ground and taking more aggressive action against Taliban fighters. This could allow US advisers to work with Afghan troops below the corps level, potentially putting them closer to fighting, a US official said.