Australian lawyer Sarah Armstrong has touched down in Launceston after being held in Mongolia for two months.

The 32-year-old was barred from leaving Mongolia in October as authorities there probed a corruption case centred on the former chief of Mongolia's mining authority.

Ms Armstrong, a lawyer for Rio Tinto mining subsidiary SouthGobi Resources, has been cleared of any involvement in the matter.

Ms Armstrong landed in Sydney on Tuesday afternoon, where she had lunch with friends before flying to her parents' home in Tasmania.

Her mother Yvonne Armstrong says her daughter's release is a Christmas miracle.

She says detention has taken its toll on her daughter, who has been travelling to Mongolia for years.

"A few weeks ago she was quite down with it all," she said.

"And I'm sure she only rang us when she wasn't upset, but a few weeks ago she did and that was pretty horrible.

"You realise just how hard it was on her."

Hantulga Galaazagraa, an attaché at the Mongolian Embassy in Canberra, says the investigation has been finalised and it is great Ms Armstrong will be home for Christmas.

"It was nothing against Ms Armstrong personally; she was asked not to leave the country so that she might have useful information about the investigation," he said.

"So she was asked to cooperate with the anti-corruption agency of Mongolia.

"Ms Armstrong is on her way back home and we are very excited about it."

Mr Galaazagraa says Ms Armstrong was interviewed four to five times, with her last interview in mid-November.

He says he does not know why it has taken so long for her travel ban to be lifted.

"It was believed the SouthGobi resources company had a tax avoidance issue and also some bribery cases against the former chief of the Mongolian Mineral Resources Authority and it was nothing against Ms Armstrong."

He says the matters involving Ms Armstrong are finalised and it is a coincidence that it is Christmas.

"It's nothing strategic about it, it's just the timing just came out for Christmas. We are very delighted she'll be able to be home for Christmas."

Mr Galaazagraa says the Mongolian government was separate to the independent investigation and was not able to influence the case or the timing of Ms Armstrong's return.

He has reassured foreign nationals they will be safe to do business in Mongolia following Ms Armstrong's release.

"Now the Mongolian government is giving signals to the foreign investors the Mongolian government is working against bribery and corruption, which is a good message to foreign investors."

Foreign Minister Bob Carr says he is pleased Mongolian authorities made the decision to lift Ms Armstrong's travel ban and allowed her to return home in time for Christmas.