The Philippines on Friday urged its mariners to "avoid" the Red Sea as Yemen-based Houthi rebels kept up their deadly missile and drone attacks on merchant shipping in the vital waterway.

"Philippine nationals should avoid the area altogether unless absolutely necessary for their livelihood," the foreign ministry said, citing the "conflict escalation in the Red Sea that poses a clear and present danger to all Filipino seafarers working in the area".

The ministry said Filipino seafarers should exercise "prudent" judgement as well as their right to refuse to sail through the risky area.

The warning came a day after 23 Filipino and two Russian crew members were rescued from a Greek-flagged oil tanker that was hit by several projectiles off the rebel-held Yemeni port of Hodeida.

The attack on the Sounion caused a fire and cut engine power.

It was claimed by Yemen's Iran-backed Houthi rebels, who have waged a campaign against international shipping that they say is in support of Gaza during the Israel-Hamas war.

The Red Sea, a key waterway between Europe and Asia, is one of the world's busiest cargo and oil transit points. 

The Philippines is a major crew supplier to the global shipping industry, with more than 400,000 mariners, according to the government.

Manila said Thursday that the Sounion was the ninth ship with Filipino crew members to be attacked by the Houthis.

One Filipino remains missing from a Red Sea attack on the MV Tutor in June, while 17 Filipino crew from the Galaxy Leader have remained in Houthi captivity since the ship was seized last November.

The Houthis said in a statement Thursday that their operations against merchant shipping "will not stop until the aggression is stopped", referring to Israel's military operations in Gaza.