The United States sanctioned two people and four firms on Wednesday for facilitating the procurement of weapons on behalf of Yemen's Huthi rebels.

The group began launching attacks on ships in the Red Sea following the outbreak of the Israel-Hamas war in Gaza, forcing many shipping companies to alter their routes and triggering retaliatory strikes by the United States and its allies.

Wednesday's sanctions targeted "procurement operatives, shipment facilitators and suppliers" based in Yemen and China who sourced dual-use equipment for use in the Huthi's advanced weapons systems, the Treasury Department said in a statement.

It said that those sanctioned had "directly supported" the Yemeni rebels' efforts to procure "military-grade materials abroad," which were then shipped to Huthi-controlled areas of Yemen, enabling their ongoing attacks.

The Huthis "have sought to exploit key jurisdictions like the PRC (People's Republic of China) and Hong Kong in order to source and transport the components necessary for their deadly weapons systems," US Treasury under secretary for terrorism and financial intelligence Brian Nelson said.

The Treasury would continue to target these "facilitators" who enable Huthi activities, he added.

Those sanctioned include Al-Shahari United Corporation, a company based in the Yemeni capital Sanaa, which allegedly relied on a branch office in the Chinese city of Guangzhou to facilitate shipments to Yemen.

The US Treasury also sanctioned a Yemeni businessman named Maher Yahya Muhammad Mutahar al-Kinai, who it said had coordinated with other Huthi operatives to "facilitate shipments of dual-use equipment and components."