LONDON - Global mining giant Rio Tinto said on Tuesday four of its employees in Shanghai had been detained by the Chinese authorities.

We aren't confirming names ... Rio Tinto is concerned about the employees' wellbeing and is doing everything possible to help them and support their families, the London-listed miner said in a statement.

The reasons for these actions are unclear. Rio Tinto intends to co-operate fully with any investigation the Chinese authorities may wish to undertake and has sought clarification on what has occurred.

Rio would not give any names or comment further. (Reporting by Pratima Desai; editing by Anthony Barker)

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