BAGHDAD — The US-led military coalition in Iraq said Friday that it was investigating reports that scores of civilians — perhaps as many as 200, according to local residents — had been killed in recent US airstrikes in Mosul, the northern Iraqi city where Iraq’s security forces have been waging a months-long offensive.

The reports of a heavy civilian toll from airstrikes in Mosul come on the back of two recent incidents in Syria, where the coalition is also battling the Islamic State from the air, in which activists and local residents said dozens of civilians had been killed.

Taken together, the surge of reported civilian deaths raised questions about whether once-strict rules of engagement meant to minimize civilian casualties were being relaxed under the Trump administration, which has vowed to fight the Islamic State more aggressively.

US military officials insisted that the rules of engagement had not changed. They acknowledged, however, that US airstrikes in Syria and Iraq have been heavier in an effort to press the Islamic State on multiple fronts.

Colonel Joseph E. Scrocca, a spokesman for the US-led command in Baghdad, said in a statement that “the coalition has opened a formal civilian casualty credibility assessment on this allegation’’ from Mosul.

“This process takes time, though, especially when the date of the alleged strike is in question,’’ he said.

Based on reports from the ground, Scrocca said the coalition was investigating reports of civilian deaths from a strike sometime between March 17 and Thursday.

New York Times