Yemen's Houthi rebels have shot down a US military drone, US officials and the Iran-aligned Houthi movement have said.

A US official said an MQ9 drone was shot down off the Yemeni coast by Houthi forces.

This was confirmed by a Houthi military spokesman.

It comes as Washington is on alert for activity by Iran-backed groups in the Middle East as its close ally Israel - Iran's main adversary - battles Hamas in the Gaza Strip.

Last month, a US navy warship intercepted cruise missiles and several drones launched by the Houthis from Yemen towards Israel.

The US has moved military assets, including aircraft carriers, Marines and support ships, to the Middle East in the wake of regional tensions surrounding the Israel-Gaza war.

This includes troops being stationed onboard military vessels in the Red Sea, which lies between Yemen and Israel.

Yemen's Houthi rebels are backed by Iran, and have been locked in a prolonged civil war with Yemen's official government - supported by another Iran rival, Saudi Arabia - since 2014.

The deputy leader of another Iran-backed group in the region, Lebanon's Hezbollah, told the BBC this week that Israel's killing of civilians in Gaza risks wider war in the Middle East.

Sheikh Naim Qassem said that "very serious and very dangerous developments could occur in the region, and no one would be able to stop the repercussions".

Meanwhile, the US also said on Wednesday that it had carried out strikes against a facility in eastern Syria that it said was used by Iran's Islamic Revolutionary Guard Corps and affiliated groups.

A Pentagon official said the strikes, the second in recent weeks, were in response to attacks against US forces in Iraq and Syria.

"While we are seeing an uptick in attacks, our purpose is to ensure that this conflict doesn't widen out beyond Israel," Deputy Pentagon Press Secretary Sabrina Singh told reporters regarding American deterrence efforts.

The Syrian Observatory for Human Rights war monitor said the strike killed nine people affiliated with Iran-backed groups in Syria, a figure that could not be independently confirmed.