A Chinese plane that held up a Royal Australian Air Force jet from landing in Vanuatu was chartered by a state-owned company that is among the biggest contractors in the South Pacific.

Australian Defence officials are looking into why the Chinese plane, which was carrying medical equipment, was still on the tarmac when the RAAF plane had been cleared to deliver humanitarian supplies on Sunday for the cyclone-struck nation.

A C-17 Globemaster leaves RAAF base for Vanuatu after Cyclone Pam in 2017.

The C-17A RAAF plane had to return to Brisbane after reaching its fuel limit while circling the airport and returned a day later to deliver the supplies.

The Chinese plane, which arrived the previous day, was chartered by China Civil Engineering Construction Corp (CCECC), which has a significant presence in the region.