UPDATE 1-Rio Tinto to start exporting Oyu Tolgoi copper on June 21 -sources
* Mongolia pressed Rio to keep export revenue in country
* Dispute with government now resolved
* Oyu Tolgoi to make up one-third of economy by 2020
ULAN BATOR, June 20 (Reuters) - Rio Tinto plans to start exporting copper from the $6.2 billion Oyu Tolgoi mine in Mongolia on Friday, after resolving demands from the government, according to a new invitation received by Reuters.
Journalists have been invited to attend a ceremony at the copper and gold mine on Friday to mark the first export, a week later than initially flagged.
The event had been postponed due to a demand from the government that Rio Tinto keep all export revenue in Mongolia, Prime Minister Norov Altankhuyag said earlier this week.
That issue has been resolved, people familiar with the issue told Reuters. The agreement that governs the Oyu Tolgoi project gives Rio Tinto the freedom to put the export revenue anywhere it wants, they added.
Given the company's accounts in Mongolia had been temporarily frozen earlier this year, keeping funds there would not be an attractive option.
Rio Tinto, operator of the mine, declined to comment on the event set for Friday. Its subsidiary Turquoise Hill Resources Ltd owns a 66 percent stake in the mine, with the Mongolian government owning the remainder.
Rio has been producing at Oyu Tolgoi for several months, and has been aiming to start exports by the end of June. But it has said since February that it would not begin exporting until it resolved disputes with the Mongolian government over royalties, costs, management fees and project financing.
In the first 10 years, Oyu Tolgoi's annual output is expected to average 330,000 tonnes of copper and 495,000 ounces of gold. By 2020, the mine could make up a third of Mongolia's economy.