Fresh maritime strikes in the Gulf choke point coincide with Houthi missile hits on Saudi Aramco and Riyadh airport.
A missile damaged an office tower at the oil giant's main complex as Houthi forces warned of further strikes against airports and energy sites.
Crude benchmarks softened after G7 powers pledged 100 million barrels of fuel and Gulf shipments climbed past pre-conflict levels.
The drone and missile strikes threaten to disrupt a fragile market recovery built on G7 reserve releases and rebounding Middle Eastern crude exports.
The reported strike on the state-owned refinery has triggered retaliatory airstrikes in Sana'a and Saada.
