BEIJING (AP) — Mining giant Rio Tinto has announced the launch of the next stage of a multibillion-dollar goal and copper mine in Mongolia following lengthy negotiations and political tension over the role of foreign companies in resource industries.

Rio said Friday said an underground portion of the Oyu Tolgoi mine will go ahead after the company, the Mongolian government and another partner agreed on a $5.3 billion investment plan. It said production should begin in 2020.

Oyu Tolgoi became a symbol of tense relations between Mongolia and foreign investors. Expansion plans were delayed by disagreement over how to share revenue in the impoverished but resource-rich country between China and Russia.

Critics of government agreements with mining companies complain too little of Mongolia's mineral wealth benefits the general public.