BAGHDAD, Iraq -- A suicide drone hit an airbase in Iraq hosting US troops on Saturday, Iraqi security sources said, but the Pentagon said it could not confirm that such an attack took place.

Armed factions close to Iran have threatened to attack US interests in Iraq over Washington's support for Israel since Hamas militants killed more than 1,400 people in a shock cross-border attack from Gaza on October 7.

Israel's retaliatory bombardment of Gaza has killed more than 4,300 people, according to its Hamas-controlled health ministry.

"The drone came down inside the (Ain al-Assad) base" in the western province of Anbar, without causing any casualties or damage, a military source told AFP on condition of anonymity.

A statement issued on Telegram channels used by pro-Iranian armed groups said the attack was carried out by a group calling itself the Islamic Resistance in Iraq.

A second Iraqi security source told AFP the attack had involved two suicide drones. "The first was intercepted and the second crashed because of a technical problem," the source said.

The Pentagon, however, said it was unaware of any such attack.

"We have not seen any operational reporting confirming" that an attack occurred Saturday, a US Defense Department official said on condition of anonymity.

Since Wednesday, three Iraqi bases used by US-led coalition troops have been targeted in five separate attacks -- Ain al-Assad, the Al-Harir base in northern Iraq and a military camp near Baghdad airport.

The United States currently has about 2,500 troops stationed at the three bases, alongside around 1,000 soldiers from other countries in the coalition set up to fight the Islamic State jihadist group.

The attacks came after factions loyal to Iran stepped up threats against the United States.

One of them, the Hezbollah Brigades, demanded that US forces "leave" Iraq, "otherwise they will taste the fires of hell".