Sinovel, the Chinese wind turbine manufacturer, has launched a $125m counterclaim against former supplier American Superconductor.

Sinovel is China’s biggest wind turbine maker by number of turbines manufactured. Its move comes after American Superconductor launched five lawsuits and arbitration proceedings against the Chinese company last month, saying that it had breached contracts and stolen intellectual property.

Clean energy co-operation between the US and China, once a bright spot in the diplomatic relationship, is under increasing strain. Last month a US senator called for antidumping tariffs on Chinese solar panels, alleging that China’s subsidies for solar panel manufacturers violate China’s commitments to the World Trade Organisation.