Australia urged China on Thursday to proceed quickly with the trial of four China-based staff of Anglo-Australian miner Rio Tinto , whose arrest on charges of spying and bribery have strained ties with Beijing.

We would hope this matter gets resolved as quickly as possible, as we have said all the way through, Australian Financial Services Minister Chris Bowen told Australian radio.

China late on Wednesday indicted the four employees, including Australian Stern Hu, Rio Tinto's top iron-ore negotiator at the time of his arrest last year. The move sets the stage for a trial in the case, which has jangled investor nerves.

China is a sovereign nation and has its own legal system. We'll be working within that legal system with his representatives to ensure that he gets whatever assistance is necessary and appropriate from the government, Bowen said.

The four are set to stand trial in Shanghai. If found guilty, they could face up to seven years in jail on the commercial secrets charge and up to 20 years on the bribery charge, said Zhang Peihong, a lawyer for one of the accused Chinese nationals.

The case also poses election-year difficulties for Australian Prime Minister Kevin Rudd, who is a China expert and under pressure from media and political opponents at home to use his relationship with Beijing's leaders to help free Hu.

China is Australia's biggest trade partner. Australia exported $15 billion worth of iron ore to China in 2008, or 41 percent of China's iron ore imports.

Australian opposition lawmakers and key minor-party senators have pointed to the Rio case as reason for the government to limit Chinese investment in Australian resource firms.

Rudd was expected to comment on the indictments later on Thursday and Canberra has previously warned China that the world is closely watching its handling of the case.

No trial date has been announced, but traditional Chinese New Year holidays beginning this weekend will likely delay the hearing for several weeks.

Rio Tinto was yet to comment on the indictments on Thursday, but has previously said its staff are innocent. The company is due to announce its annual results later on Thursday.

(Reporting by Rob Taylor; Editing by )