Rescuers pulled six crew members alive from the Red Sea after Houthi militants attacked and sank a second ship this week, while the fate of another 15 was unknown after the Iran-aligned group said they held some of the seafarers.

Germany said its aircraft was in the middle of a routine flight in support of the European Union's counter-Houthi mission.

Two crew members of a Liberian-flagged cargo ship have been killed in an attack in the Red Sea off the coast of Yemen, Liberia says. A Liberian representative to the International Maritime Organization (IMO) said the Eternity C was "attacked horribly... causing the death of two seafarers".

Oil prices edge higher in volatile trading as investors weigh a sharp rise in U.S. crude inventories and global trade risks against attacks on shipping in the Red Sea. Brent crude rises 0.4% to $70.45 a barrel, while WTI is up 0.5% to $68.70 a barrel.