Jailed Rio Tinto executive Stern Hu believes Prime Minister Tony Abbott must directly raise his case with China's President Xi Jinping for him to have any chance of being released early.

Hu's personal plea to Mr Abbott, relayed via friends and senior government figures, reflects an evolving consensus that China is returning to a style of "emperor" politics, where all significant initiatives and favours from the state must come through Mr Xi personally.

Imprisoned in China: Stern Hu.

In recent communication Hu has described himself as a "prisoner of the emperor".

Australian leaders have lobbied for lenient treatment since Hu's shock arrest on national security grounds in July 2009, at the height of the "iron ore wars". He was nevertheless sentenced to 10 years' jail for bribe-taking and industrial espionage.