Saudi-led coalition forces said on Wednesday they had seized an Iranian fishing boat loaded with weapons on its way to deliver them to Houthi fighters in Yemen.
The announcement came a day after tribal fighters backed by the coalition won control of a strategic dam in central Yemen from Houthi forces following weeks of fighting east of the capital Sanaa.
The coalition, which also includes Bahrain, Qatar, Egypt and the United Arab Emirates, has been battling the Iranian-backed Houthis for more than six months.
It aims to restore to power President Abd-Rabbu Mansour Hadi's government, forced out by the Houthis, and contain what Gulf Arab states see as Tehran's growing influence in their backyard.
As part of the campaign, Saudi-led naval forces have imposed a near-blockade to prevent weapons from reaching the Houthis, resulting in long delays and mandatory searches for shippers in the region.
A coalition statement said 14 Iranian sailors were detained on the boat, which was carrying 18 anti-armoured Concourse shells, 54 anti-tank shells, shell-battery kits, firing guidance systems, launchers and batteries for binoculars.
"The Command of the Coalition ... foiled an attempt to smuggle weapons destined to the Houthi militias, on an Iranian fishing boat," the statement said, adding the vessel was seized on Saturday some 150 miles off Salalah in southern Oman
There was no immediate comment from Iran.
The coalition has long accused Iran of arming the Houthis, who seized control of Yemen starting in September last year, claiming they were out to fight corruption and to force Hadi to bring them into the government.
The seizure of the Marib dam is the biggest success for several weeks for the Yemeni militia fighting alongside Gulf troops. Together they have pushed toward the Houthi-controlled capital Sanaa 110 km (70 miles) west of the dam, but progress has been slowed by landmines and stiff resistance from Houthi forces in rugged mountains.
Pictures on the front pages of Gulf dailies showed the foreign troops and local tribesmen planting the flags of the UAE, Bahrain and Saudi Arabia on the dam.
Two suspected al Qaeda militants were killed in what was believed to be a U.S. drone strike on a vehicle travelling in al-Wadi district in Marib on Wednesday, local tribesmen said.
U.S. forces have conducted many strikes in the area. Washington acknowledges using drones against militants but does not publicly comment on the operations.
Further to the southwest, pro-Hadi fighters suffered their first significant loss in weeks in Taiz province, where a district fell to the Houthis and their allies in Yemen's army on Tuesday.
Residents and local officials said the Houthis appeared to be mobilising their forces for a southern push in the nearby area of Kirsh, about 75 km (45 miles) from Aden.
Six months of civil war and hundreds of coalition air strikes have killed more than 5,400 people in Yemen, according to the United Nations
, and exacerbated widespread hunger and suffering.
(By William Maclean; Additional reporting by Mohammed Ghobari and Marwa Al-Malik; Writing by Noah Browning and Sami Aboudi; Editing by Andrew Roche)