Houthi militants attacked a Saudi warship with three boats off the western coast of Yemen on Monday, causing an explosion that killed two crew members and injured three others, Saudi state news agency SPA reported.
"A Saudi frigate on patrol west of Hodeidah port came under attack from three suicide boats belonging to the Houthi militias," the Saudi-led coalition fighting in Yemen said in a statement on SPA.
One of the boats collided with the rear of the vessel, causing an explosion and a fire that killed two crew members, the statement said, without specifying their nationality.
Three others were injured and in a stable condition. The fire was put out by crew.
The Iran-allied Houthi group that controls Yemen's capital claimed responsibility for the attack, the third carried out on ships off the coast of Yemen in the last six months.
"The Saudi warship was involved in aggression against western coastal cities and Yemeni fishermen," a military official was quoted as saying by the Saba Yemeni news agency, run by the dominant Houthi movement.
Earlier on Monday, a building in southern Saudi Arabia used by United Nations staff to monitor ceasefire violations in Yemen was damaged by cross-border rocket fire.
The Saudi-led coalition said the attack on the ship was a serious development that "would impact international navigation and the flow of humanitarian assistance to the port for Yemeni citizens."
In October, a US Navy guided missile destroyer was targeted in a failed missile attack from Yemen.
Former President Barack Obama launched cruise missile strikes on coastal radar sites in response in Washington's first direct military action against suspected Houthi-controlled targets in Yemen's conflict.
In another incident in October, a Saudi-led force rescued passengers from a vessel being used by the UAE military that was attacked by Houthi fighters in a strategic Red Sea shipping lane, the Bab al-Mandab strait.
More than 3.4 million barrels of oil passed through the 20 km (12 mile)-wide Bab al-Mandab each day in 2013, the US Energy Information Administration says.
Saudi Arabia and its Gulf Arab allies have carried out thousands of bombing raids in Yemen since March 2015 in a campaign to try to restore the ousted internationally recognised government of President Abd-Rabbu Mansour Hadi.