Aden|Dubai|Cairo: Yemen's Iran-backed Houthi rebels captured a strategic island in the Bab el-Mandeb Strait at the entrance of the Red Sea, two officials said on Friday. The swift advance further threatens Saudi Arabian oil exports through one of the world's key commercial lanes amid the West Asia turmoil.The island, known variously as Perim and Mayun, is about 3.5 km off Yemen's coast. It's capture was confirmed by a senior military official with Yemen's internationally recognised government and by a Houthi official. Both spoke on condition of anonymity.Barrel of woesBab el-Mandeb is a key alternative to Strait of Hormuz, caught in the middle of warfare between Iran and the US. Its control could give Tehran a critical advantage, reducing supplies through a second major transit corridor and sending oil prices surging.But there is "no need for international concern," said Hazam al-Assad, a member of the rebels' political bureau. He said they were responding to Saudi aggression, and "our forces have a bank of big important targets," in case Riyadh keeps up the strikes.US President Donald Trump has reportedly refused Saudi Arabia's call to launch strikes against the Houthis.Earlier, two officials from the Saudi-backed, recognised Yemeni government said its forces had pulled out of Perim and that the Houthis had also taken the mainland Red Sea town of Dhubab, which faces the island.Saudi Arabia, the world's largest oil exporter, has relied on Red Sea route since the Iran conflict effectively closed Strait of Hormuz, through which a fifth of global oil used to flow.