Yemen's Iran-backed Houthis took control of the Bab el-Mandeb strait on Friday, after capturing an island located in the middle of the crucial Red Sea waterway, a local government official and eyewitnesses said.

"Boats carrying armed Houthi fighters reached Mayyun Island after government forces withdrew from it yesterday," the official said, referring to a rocky volcanic island also known as Perim that divides the narrowest part of the strait into two shipping lanes.

"The Houthis have completed their takeover of the Bab el-Mandeb area and Mayyun Island, which is located in the middle of the strait," he added, speaking on condition of anonymity.

An eyewitness said gunmen were "deploying along the Bab el-Mandeb shore and are driving around in military vehicles."

On Thursday, Houthis captured the strategic port city of Mokha from government forces in a blitz offensive that also saw them taking control of Zuqar Island in the southern Red Sea "after rocket attacks and a ground assault carried out using boats transporting fighters," according to military sources.