"Our first priority is protecting coalition personnel," the official said, saying the US-led force had "limited" their training and other anti-jihadist operations.

"It's not a halt," the source said, adding: "We have increased security and defensive measures at Iraqi bases that host coalition troops."

The official said the change came after a series of rocket attacks by pro-Iran factions on US troops in recent months.

Surveillance efforts were now focused on potential new attacks instead of the Islamic State group.

The rocket attacks, which killed one American contractor last month, have stoked fears of a proxy war between the United States and Iran on Iraqi soil.

Those worries skyrocketed Friday after a US strike in Baghdad killed Iranian general Qasem Soleimani, the head of the Islamic Revolutionary Guards Corps' Quds Force foreign operations arm.

The strike also killed the deputy head of Iraq's Hashed al-Shaabi, a network of mostly Shiite factions close to Iran and incorporated into the Baghdad government's security forces.

On Saturday, the Hashed said a new strike had hit a convoy of their forces north of the capital, with Iraqi state media blaming the United States.

But the spokesman for the US-led coalition denied it.

"There was no American or coalition strike," Myles Caggins told AFP.