Yemen's Iran-backed Houthi movement has warned global shipping companies against loading or unloading cargo at Saudi Arabian ports, saying vessels that do so could face sanctions and even be targeted "in any location" within the group's operational reach, according to an email seen by Reuters.

The warning comes a day after the Houthis announced an immediate naval blockade against Saudi Arabia, significantly widening the regional shipping crisis amid the ongoing US-Iran conflict.

The move raises fresh concerns over global energy supplies and maritime trade, which are already under pressure because of disruptions in the Strait of Hormuz.

According to a Reuters report, the email, dated July 20, was sent to multiple companies in the shipping industry by the Houthis' Sanaa-based Humanitarian Operations Coordination Center (HOCC), the body responsible for issuing maritime advisories during the group's previous attacks on commercial shipping.

Warning issued to shipping companies

According to the email, all vessels are prohibited from loading or discharging cargo at Saudi ports.

"Vessels are banned from loading or discharging cargo at or from any Saudi ports," the communication said.

The Houthis urged shipping firms to exercise "due diligence and the utmost care" in their operations, warning that any vessel violating the directive could face punitive action.

The email stated that the new restrictions came into force at 1201 GMT on July 20.

It further warned that vessels engaging with Saudi ports would be exposed to sanctions and "may be subject to targeting in any location within the operational reach of the Yemeni Armed Forces."

Blockade raises fears over global trade

The latest warning follows the Houthis' announcement on Monday of a naval blockade against Saudi Arabia, opening a potential new front in the wider regional conflict involving the United States and Iran.

Houthi military spokesperson Yahya Saree described the blockade as an "eye for an eye" response to what he called Saudi actions against Yemen. The group said the embargo would take effect immediately.

Analysts say any disruption at the southern entrance to the Red Sea could remove a key alternative route to the Strait of Hormuz, increasing the risk of supply shortages and further disrupting global trade.