"Rockets were launched at Ain al-Assad base" in Anbar province, said the military source.

While some "fell inside the base", one rocket landed on a nearby village without causing any damage, the source added.

A commander in a pro-Iran armed group told AFP that at least "two rockets targeted" the base, without saying who had carried out the attack.

Another source in the group confirmed an attack occurred.

All sources spoke on condition of anonymity because they are not authorised to speak to the media.

Such attacks were frequent early in the war between Israel and Hamas Palestinian militants in Gaza but since then have largely halted.

But the latest rocket attack comes as fears grow of an attack by Iran and its allies on Israel in retaliation for the killing of top Hamas and Hezbollah figures last week in strikes either blamed on or claimed by Israel.

It also occurred after US forces carried out an air strike Tuesday night on pro-Iran Iraqi fighters who were attempting to launch drones that were deemed a threat to American and allied troops, a US official said.

The strike, which Iraqi sources said left four killed, was the first by American forces in Iraq since February.