Police are investigating whether the food served on board the missing Malaysian airliner was poisoned.

They are also retracing every piece of cargo that was loaded on to the Boeing 777, including tonnes of mangosteens, a tropical Asian fruit with a leathery shell surrounding fragrant white flesh.

The search for the missing plane continues off the coast of Perth. Credit:AP

Malaysia’s top police officer Khalid Abu Bakar said the plane’s food caterers were being scrutinised in an investigation that has so far failed to uncover any significant leads into the disappearance of the plane with 239 people on board on March 8.