A once drug-addled elephant fed heroin-laced bananas by illegal traders will return home after emerging clean from a three-year detox programme on China's tropical island province of Hainan.

The four-year-old bull elephant, referred to alternately as "Big Brother" or "Xiguang" in state media reports, was captured in 2005 in southwest China by traders who used spiked bananas to control him.

After police arrested the traders and freed Xiguang a few months later, the elephant was confirmed to be suffering from withdrawal symptoms and sent to a wild animal protection centre in Hainan for rehab, Xinhua news agency said.

A year of methadone injections at five times the human dosage had helped wean Xiguang off his addiction.

Now clean, Xiguang was expected to arrive on Saturday at a wildlife park in Kunming, capital of the elephant's home province of Yunnan on the mainland.

Xiguang's return would cap a 1,500-km journey home, Xinhua said, and mark another step in the elephant's triumph over addiction.