Yemen's Iran-backed Houthi rebels attacked two crude oil tankers - the Saudi-flagged Amjad and the Panama-flagged Blue Lagoon I - in the Red Sea on Monday, the U.S. military said, calling the assaults "reckless acts of terrorism".

The Houthis late on Monday claimed responsibility for targeting the Blue Lagoon with multiple missiles and drones but did not make any mention of the Saudi tanker.

The U.S. Central Command said the Houthis attacked the two tankers with two ballistic missiles and a one-way attack uncrewed aerial system, hitting both vessels.

Both vessels were laden with crude oil, with the Amjad carrying about two million barrels of oil, according to the U.S. military statement, which described the attacks as "reckless acts of terrorism by the Houthis."

Two sources told Reuters earlier that the ships were sailing near each other when they were hit but were able to continue their voyages with no major damage assessed or any casualties.

The Amjad's owner, Saudi national shipping group Bahri, did not immediately respond to a request for comment. The supertanker has a maximum capacity of 2 million barrels.

The Greek manager of the Blue Lagoon I, Sea Trade Marine SA, was not immediately available for comment. The Suezmax tanker has a maximum capacity of 1 million barrels.

One of the sources told Reuters the Amjad was unlikely to have been directly targeted.

Saudi Arabia, the world's top oil exporter, has watched with alarm as Houthi missiles have been fired over its territory to target ships in the Red Sea. Saudi Arabia has tried to extract itself from a messy war in Yemen and a destructive feud with the Houthis' principal backer, Iran.

The Houthis first launched aerial drone and missile strikes on the waterway in November. They say they are acting in solidarity with Palestinians under assault in Israel's war on Gaza that has killed tens of thousands, flattened most of the enclave and caused a humanitarian crisis following Palestinian Islamist group Hamas' deadly Oct. 7 attack.

In more than 70 attacks, the Houthis have sunk two vessels, seized another and killed at least three seafarers.