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Vessels travelling along the strategic route should remain vigilant of remote-controlled booby-trapped boats or rocket launchers, the government said, after two commercial carriers were attacked near the Yemeni isle of Perim.

"In previous situations of the sort, attacks were launched via hand grenades, or rocket-propelled grenades," a statement said.  

"However, the last two attacks involved booby-trapped boats which blew up some distance away from the targeted ship, however the intention was to detonate the hull."

The attack happened near Perim, or Mayun in Arabic, an island that commands the strategic strait and has been controlled by Saudi-led coalition forces since 2015 when they seized it from Yemen's Houthi rebels.

The shipping lane connecting the Indian Ocean with the Suez Canal and the Mediterranean beyond is a key transit route for oil and gas from the Gulf, and Washington has also expressed growing concern about its security.

In January, Houthis attacked a Saudi frigate off the Yemeni coast killing two sailors in what the coalition said was a suicide attack.

In September and October, two US warships and a United Arab Emirates vessel contracted to the coalition were targeted by missile fire from rebel-held territory.

In March, the head of US Central Command, General Joe Votel, warned that coastal defence missiles, radar systems, mines and explosives boats deployed by the rebels posed a threat to shipping in the strait.

The Saudi-led coalition has patrolled the waters off Yemen to enforce a blockade of rebel-held areas since it launched a military intervention in support of the government in March 2015.

However, there has also been a resurgence in attacks on shipping in the area by Somali pirates in recent months.