The Italian father embroiled in an international custody battle has left Australia after giving up hope he will win his legal fight to get his daughters back to Italy.

The father - who cannot be identified for legal reasons - flew out of Australia on Friday morning without telling any of his local supporters he was leaving. He contacted them from a stopover in Abu Dhabi to tell them he had "had enough", and was on his way back to Italy.

Despair ... the father caught up in an international custody battle has "had enough" and returned to Italy. Credit:Michelle Smith

The 35-year-old has been in Australia since May trying to engineer his daughters' return to Italy. Born and raised there, the sisters, aged nine, 10, 13 and 15, were brought to Queensland by their Australian mother two years ago on the pretext of a holiday - and stayed.

Supporters said the "very emotional and angry" father made the snap decision to abandon his fight for custody after his daughters made it clear on Wednesday they would resist any court orders to return them to Italy for a custody hearing.