Mining giant Rio Tinto has halted shipments of copper concentrate from its giant Oyu Tolgoi copper mine following a week-long dispute at the border crossing to China and a new tax bill from the Mongolian government. A dispute between Chinese trucking companies and Mongolian officials over health insurance for drivers has halted coal and copper transport at the remote Gants Mod crossing for over a week. The mine is once again under political pressure, with Mongolian politicians claiming the country has seen too little benefit from its massive expenditure. The high costs of financing the mine mean that the government will not see its share of profits for several years, although Ulan Bator does receive tax revenues. Also this week, Rio Tinto’s Canadian-listed subsidiary Turquoise Hill, which holds the shares in the Oyu Tolgoi mine, revealed a new bill for $155m in back taxes, following a Mongolian audit of 2013-2015 tax payments by the mine. The company said it is disputing the assessment.