Australian defence officials are looking to how a plane from China held up a Royal Australian Air Force aircraft from landing in Vanuatu while carrying vital humanitarian supplies for the cyclone-struck nation.

The RAAF plane carrying aid was due to land in Vanuatu's capital Port Vila on Sunday, but turned around and returned to Australia when it realised a Chinese plane with medical equipment was also on the airport's tarmac.

A destroyed building in Luganville, Vanuatu. Credit:AAP

The plane from China carrying donated medical supplies to fight COVID-19 had landed at the airport the previous day.

The Australian plane had been given full approvals to land by local authorities and was circling the airport, but the decision was made to return to Brisbane when it reached its fuel limit.