Yemen's Houthi rebels continued an hourslong attack Tuesday targeting a Liberian-flagged cargo ship in the Red Sea, authorities said, after the group claimed to have sunk another vessel in an assault that threatens to renew combat across the vital waterway.

A Liberian-flagged cargo ship came under fire on Monday in the Red Sea, with two security guards on board reportedly hurt and two others missing in an assault that came after Yemen's Houthi rebels purportedly sunk another vessel in a similar attack.

Two commercial vessels targeted in 24 hours raise fears of an escalated campaign against Israel-linked shipping.