Former Gisborne man Willie Rare remains in a Balinese jail without being charged, nearly 40 days after he was allegedly found to have a small quantity of cocaine near his home on the Indonesian holiday island.

Police arrested him on June 30 after receiving information from a resident.

They followed him into Pepito supermarket in Tuban near Bali's international airport on the southern end of the island, and say they found 3.58 grams of cocaine in his wallet.

Mr Rare, who changed his name to Angus McGaskill after moving to Australia about 30 years ago, told reporters he had made "a silly mistake" and used the drug for the first time the day before he was arrested.

Family members in Gisborne have been in regular contact with Mr Rare during his month in prison but say there is little they can do until charges are laid.

"We just have to go with their process," one of his sisters said this week.

Mr Rare was being well treated in jail, she said.

He was able to make calls with his cellphone, had access to the internet, and had made some friends there.

Before he was arrested, Mr Rare worked as a business broker in Melbourne and enjoyed regular holidays in Bali.

His family and friends say he is well educated and has not been in trouble with the law before.

It is understood Australian diplomatic services will help with defence costs once charges have been laid.