Rio Tinto Plc (RTP) has asked its foreign staff members based in China to leave or stay out of the country after four of its Shanghai-based employees were detained on July 5, a person familiar with the matter said Thursday.

Most of the foreign staff were on holiday during the time, and were asked not to return, the person said.

It was unclear if all Rio Tinto's foreign staff have since left China.

The person said it was also unclear when Rio would allow the Anglo-Australian miner's foreign staff to return to China.

The company has accounted for all its personnel and knows where each is, the person said earlier Thursday.

The person said an earlier report by the Australian Financial Review wasn't entirely correct. The Review said Rio Tinto pulled out all its China staff involved in research work on the iron ore and steel industry.

Rio Tinto executive Stern Hu, an Australian, has been detained in China since July 5 along with three Chinese colleagues on accusations that they engaged in espionage and bribery to obtain "state secrets" relating to iron ore price talks.

-By Chuin-Wei Yap, Dow Jones Newswires; 8610 6588 5848; chuin-wei.yap@dowjones.com