A rescue operation is underway after a boat reportedly transporting 100 migrants capsized when passengers shifted to one side of the vessel to reach safety.

According to local reports, at least five people have died and a baby is missing after the boat capsized at around 9:30am in the port of La Restinga on El Hierro, Canary Islands.

It is currently unknown whether the victims lost their lives in the accident or had died earlier during the crossing, a spokesperson for the Government Delegation told EFE.

Images from the scene showed Salvamar Maritime Rescue towing the small vessel through the waters, but the boat capsized just five metres from the dock as occupants prepared to disembark onto a rescue boat.

As passengers were being transferred from the boat to the Maritime Rescue vessel for passage to the port, many of the occupants tried to quickly approach the rescue vehicle when the small boat capsized, its weight falling on to one side.