China has revealed to Australian diplomats that they will not be granted access to part of the trial of an Australian employee of Rio Tinto charged with commercial spying, Canberra posted on Friday.

The Australian Department of Foreign Affairs and Trade claimed that it is highly disappointed with Beijing over the ruling and revealed that it will not initiate further attempts to permit officials access.

"If there were links, you would have expected the trade had fallen, yet last year China became our largest trading partner the two matters are separate", Crean told Australian radio.

"We've never sought to make any link and neither have the Chinese in their discussions with us", he further added.

It is revealed that the case resulted in a massive resistance between Australia and China in mid-2009 amidst a drive among Chinese companies to buy more Australian raw materials, such as iron ore and coal.

China reportedly arrested four Rio staff members, including Australian citizen Stern Hu, last July and their trial are revealed to take place in Shanghai on March 22 on charges of bribery and stealing business secrets.

China is Australia's biggest trade partner, with trade worth $53 billion last year.