A Filipino sailor was killed when Yemen's Huthi rebels attacked a bulk cargo carrier last week, the White House said Monday, condemning their actions as terrorism.

The Iran-backed Huthis have launched dozens of drone and missile strikes in the vital shipping zones of the Red Sea and the Gulf of Aden since November, describing them as retaliation for the Israel-Hamas war.

But National Security Council spokesman John Kirby said the Filipino seaman killed was on the M/V Tutor, a Liberian-flagged, Greek-owned ship that had "nothing to do with the conflict in Gaza."

The vessel suffered serious flooding and was abandoned after it was struck by a sea drone off rebel-held Hodeida on Wednesday, according to a security agency operated by the British navy.

Kirby also said that a Sri Lankan crew member was critically wounded in a separate Huthi attack on Thursday on the M/V Verbena, a Palauan-flagged, Ukrainian-owned, Polish-operated ship.

"This is pure terrorism. There's simply no other word for it. The Huthi claim of supporting Gazans is meritless," Kirby told reporters.

He also referenced newly announced US sanctions that the State Department said will target three individuals and six entities involved in the Huthi's weapons procurement network.

The State Department said Monday the sanctions targets "have enabled Huthi forces to generate revenue and acquire a range of materials needed to manufacture the advanced weaponry they use to conduct ongoing terrorist attacks against US and allied interests."