Rio Tinto on Thursday night slammed Chinese steelmakers over increasingly aggressive negotiating tactics, after the China Iron & Steel Association called for its members to boycott the Anglo-Australian mining group’s spot sales of iron ore.

The steelmakers have failed to agree a 2008-2009 annual contract price with Rio and BHP Billiton despite months of talks. Earlier this year, the Chinese authorities delayed issuing permits needed to import some shipments of Australian iron ore, a move that was also considered a negotiating ploy.