All of the ships were travelling to or from Saudi ports before changing course, ship-tracking data shows.

At least seven oil tankers have made U-turns close to Yemen since the Iran-linked Houthi group announced a "maritime embargo" against Saudi Arabia on Monday, ship-tracking data shows. All of the ships were travelling either to or from Saudi ports and made sharp changes of course after the embargo was announced. Nearly 15% of global sea trade moves through the Red Sea, which connects the Mediterranean and Gulf of Aden through two choke points - the Suez Canal in Egypt and the Bab al-Mandab Strait between Yemen and the Horn of Africa. The Red Sea has been a key route for exports of Saudi oil since the US-Israeli war with Iran led to the effective closure of the Strait of Hormuz, which has severely restricted the flow of oil and gas from the Gulf. This has played a "major role in relieving pressure to global markets" and if the Houthis further restrict trade then "prices will go up", said Rosemary Kelanic from the US-based Defense Priorities think tank. The day before the Houthis announced their blockade, 20 vessels entered the Red Sea and 22 exited via the Bab al-Mandeb strait, according to maritime intelligence firm Kpler. Kelanic told BBC Verify that any Houthi attacks on vessels in the Red Sea or Gulf of Aden "will suppress all international traffic not just Saudi-bound vessels". The EU's naval force in the region Aspides recommended on Wednesday that "merchant vessels linked to Israeli, US or Saudi interests avoid transiting the Red Sea and Gulf of Aden until the threat level decreases", according to an advisory seen by Reuters news agency.