The Hong Kong arm of a major Australian mining company based in Mongolia has yet to comment on why its senior lawyer is still being questioned by anti-corruption authorities and banned from leaving the country.

Australian lawyer Sarah Armstrong, 32, joined South Gobi Resources – a subsidiary of mining giant Rio Tinto – about 2-1/2 years ago as chief legal counsel, moving from Australia to Hong Kong.

Armstrong was stopped from boarding a flight from the capital, Ulaanbaatar, two weeks ago.

It is believed that officials from Mongolia”s Independent Authority Against Corruption wanted to question her as a witness to alleged corruption and money-laundering. It is understood this is not the first time the company”s staff have been banned from leaving the country.

No charges have been laid and Armstrong has not been detained.

Company spokesman Dave Bartel refused to comment on the nature of the investigation. He said: “It”s a difficult time for her but she is free to move around and visits friends and work colleagues, and comes to the office in Mongolia.

“We”re giving her round-the-clock assistance and doing everything possible to resolve the situation. We”re in contact with her family in Australia and very grateful for the excellent support she is receiving from Australia”s Consul General in Mongolia.”