Boat carrying refugees was travelling to Sudan when it was hit by airstrike from Apache helicopter, coastguard says.

Thirty-one Somali refugees were reportedly killed off the coast of Yemen late on Thursday when a helicopter attacked the boat they were travelling in, a coastguard in the Houthi-controlled Hudaydah area has said.

Mohamed al-Alay said the refugees, carrying official UNHCR documents, were travelling from Yemen to Sudan when they were attacked by an Apache helicopter near the Bab el-Mandeb strait.

A sailor who had been operating the boat, Ibrahim Ali Zeyad, said 80 refugees had been rescued after the incident.

While the identity of the helicopter was not immediately clear, Saudi Arabia, which is leading a coalition in the war in Yemen, has US-built Apache A-64 Longbow attack helicopters.

The kingdom’s Al-Madinah class frigates, one of which was damaged in an attack by a Houthi militia in January, is also capable of carrying a single helicopter. Other naval forces operating in the area are also equipped with helicopters, including the US military.

The incident on Thursday followed previous targeting of naval vessels last autumn. In October, two service personnel were killed when a United Arab Emirates vessel was hit. Later that month, the USS Nitze and USS Mason came under anti-ship missile fire.

US retaliatory fire destroyed several Houthi-controlled radar sites in and around the port of Hudaydah – the same immediate area where the refugee boat was struck – with cruise missiles. Hudaydah is controlled by Iran-allied Houthi fighters who in 2014 overran Yemen’s capital, Sana’a, and forced the Saudi-backed government of Abd-Rabbu Mansour Hadi to flee into exile.

While the Houthis are less well equipped than the Saudi coalition, one of their most sophisticated weapons has been its missile systems.

A Saudi-led coalition was formed in 2015 to fight the Houthis and troops loyal to former President Ali Abdullah Saleh who have fired missiles into neighbouring Saudi Arabia.