The Mozambican Airlines plane that crashed in November was "deliberately" brought down by the pilot, an initial investigation by aviation authorities has revealed.

Joao Abreu, the chief of the Mozambican Civil Aviation Institute (IACM), said Captain Herminio dos Santos Fernandes caused the crash.

The crash of flight TM470, which involved an Embraer 190 aircraft built in October 2012, killed all 33 people on board - six crew members and 27 passengers, most of them Angolans and Mozambicans, though Chinese, French, Portuguese and Brazilian nationals also perished.

Preliminary reports suggest the captain of the flight, from the Mozambican capital Maputo to Angola's Luanda, locked himself in the cockpit and ignored warning calls during the final moments of flight.

"During these actions you can hear low and high-intensity alarm signals and repeated beating against the door with demands to come into the cockpit," Abreu told the state-run news agency AIM.

The authorities have refused to speculate on the pilot's motives, as the investigation continues.

Dos Santos Fernandes had clocked more than 9,000 flying hours and had cleared a medical examination in September 2013.

Mozambican Airlines is one of several carriers in the southeast African country that have been banned from European airspace since 2011 over safety concerns.