Australian police were on Tuesday investigating how a 12-year-old boy managed to fly alone to the Indonesian island of Bali and spend four days at a resort using his parents' credit card.

The boy ran away from his Sydney home after a row with his mother, flying first to the Western Australian city of Perth on budget airline Jetstar and then on to Bali, according to commercial broadcaster Channel Nine.

"He just doesn't like the word 'no', and that's what I got, a kid in Indonesia," his mother, Emma, told Channel Nine in a programme that aired late Monday.

"It's too easy, it's way too easy. There's a problem in our system," she said, calling for tighter controls on air travel by young people.

The family had previously visited Bali on holiday and Emma said her son had already tried to book flights there on his own but had been knocked back by airlines because he did not have a letter from her.

"We screamed, we begged for help (from Australian authorities) for weeks on end," Emma added.

"When the first attempt to Indonesia took place, we were told his passport was going to be flagged."