US Naval Forces Central Command, or NAVCENT, said it boarded the boat on December 20 in the North Arabian Sea, seized the weapons cache and five crew members -- who identified themselves as Yemeni -- before scuttling the vessel.

Yemen has been wracked by civil war since 2014, pitting Iran-backed Huthi rebels against the internationally-recognised government.

"US 5th Fleet ships seized approximately 1,400 AK-47 assault rifles and 226,600 rounds of ammunition from a stateless fishing vessel," a US navy statement Wednesday read.

"The stateless vessel was assessed to have originated in Iran and transited international waters along a route historically used to traffic weapons unlawfully to the Huthis in Yemen."

The Bahrain-based US 5th Fleet has seized approximately 8,700 illicit weapons this year.

The United States as well as ally Saudi Arabia -- which is leading the military coalition backing the Yemeni government against the rebels -- have long accused Iran of supplying the Huthis with weapons, a charge Tehran denies.

"The direct or indirect supply, sale or transfer of weapons to the Huthis violates UN Security Council Resolutions and US sanctions," the US statement added.

The five crew members will be repatriated, the navy said, adding that the boat was sunk because it was a "hazard" for commercial shipping.

Riyadh has said that its 2015 intervention in Yemen was aimed at preventing an Iranian ally taking power on its doorstep.

In recent days, fighting in Yemen has seen Saudi-led coalition forces carry out air strikes on the rebel-held capital Sanaa.

On Wednesday, the coalition said it targeted a Huthi military camp in Sanaa, and destroyed seven drone and weapons storehouses, according to the official Saudi Press Agency.

Earlier this week, it targeted Sanaa airport, whose operations have largely ceased because of a Saudi-led blockade since August 2016, with exemptions for aid flights.

The UN estimates Yemen's war will have claimed 377,000 lives by the end of the year through both direct and indirect impacts.

More than 80 percent of the population of around 30 million require humanitarian assistance.