A 14-year-old Australian boy has been detained by police in Bali after he was allegedly found with a small quantity of marijuana.

The boy, from Newcastle in New South Wales, is understood to be in the custody of police in Denpasar.

He was arrested on Tuesday, and is understood to have been carrying 6.9 grams of marijuana.

The Australian Department of Foreign Affairs says he has not yet been charged.

His parents are in Bali with him and they are seeing a high profile lawyer who has previously handled the defence of other Australians on drug charges in Bali.

The boy is believed to be the youngest Australian arrested in Indonesia under the country's harsh anti-drugs laws.

Sorry, this video has expired Australian teenager arrested in Bali for marijuana

Foreign Minister Kevin Rudd says the Australian Government is working closely with Indonesian authorities to obtain the release of the boy.

"I have just spoken with our ambassador in Jakarta (Greg Moriarty) and I have indicated to him that his number one priority in the immediate period ahead is how we support this young boy and his family and do everything we can to obtain his early return to Australia," he said.

Mr Rudd says the consul and the consul general are having "rolling" contact with the family and that his heart goes out to the parents.

"I think if you put yourself in the position of being a mum or a dad with a 14-year-old who's got themselves caught up in this situation, you're heart would go out to the parents."

The boy, who was on holidays with his parents and staying in the luxury resort area of Legian, was with a friend when he was arrested on Tuesday afternoon.

It is alleged he bought the marijuana for the equivalent of $25 after being approached by a dealer while on his way to get a massage in Kuta earlier in the afternoon.

Police then detained him outside a supermarket after he left the place where he received the massage.

If he is charged with possession, he would face a maximum penalty of 12 years in prison.

However, his lawyer, Mohammad Rifan, says he could be charged under provisions for juveniles, in which case the maximum penalty would only be six years.

Under Indonesian law, there is no juvenile court system, so if he is charged the boy is likely to be placed in an adult prison.

Mr Rudd says he will not go into the facts of the boy being held, but that the Government is working closely with the Indonesian authorities.

"Regrettably, we know the authorities in Denpasar too well through matters we have had to deal with over the years," he said.

"I'm not going to be in the business of providing public lectures from abroad on the nature of anyone else's legal regime."

He says his job is to try and get the boy home.

"We respect those laws and we will work very closely with our friends and colleagues in Jakarta and Denpasar," he said.

The arrest is the latest in a string of drug-related arrests of Australians in Bali in recent years.

Graeme Michael Pollock, from Darwin, was arrested last month with a small amount of methamphetamine. He is also yet to be charged.

A host of other Australians have been jailed for drug-related offences and are serving time in Bali's Kerobokan Prison, including the Bali Nine, the Gold Coast's Schapelle Corby and Sydney man Michael Sacatides.

Two other Australians, Ricky Rawson from Victoria and Melbourne man Angus McCaskill, were released from jail earlier this year after serving time in Kerobokan.

ABC/AAP