Mongolia’s government is said to be actively seeking to cancel a deal with Rio Tinto (ASX, LON, NYSE: RIO) governing a $6.75 billion expansion of the Oyu Tolgoi copper mine in the Gobi Desert, as it looks to replace it with a new agreement.

Rather than acting unilaterally, which would risk future foreign investment projects, local authorities have suggested Rio Tinto to mutually terminate the plan. The end goal, the Financial Times reports, is to reach a new agreement more beneficial to Mongolia.

Ulaanbaatar threatened in early January to halt construction at the mine, arguing that delays and higher-than-expected costs had eroded the economic benefits the country had hoped for.

Rio had, in 2019, flagged stability risks associated with the original project design, which translated into as much as an additional $1.9 billion cost and a 30-month delay.

The miner confirmed in December the new estimate for the long-awaited underground expansion, adding that production would begin in October 2022.

Erdenes Oyu Tolgoi LLC, the Mongolian state-owned company that owns a third of the mine, reacted to the new timeline and budget by saying that Rio had not delivered on its 2015 promises.

The Mongolian Parliamentary Working Group, formed in 2019, recommended exploring possibilities for a production sharing agreement and/or replacement of the equity interest with a special royalty.