AlHijjah 23, 1433, Nov 8, 2012, SPA -- The European Union on Thursday launched an investigation into whether the Chinese government has been unfairly subsidizing solar panel producers, in a move further straining ties already tested by an anti-dumping probe into the industry, as dpa reported. "In terms of value of imports affected, this is the most significant anti-subsidy complaint the European Commission has received so far," the EU's executive said in a statement. "In 2011, China exported solar panels and their key components worth around 21 billion euros (27 billion dollars) to the EU," it added. China is the world's largest producer of solar panels. A European industry association, EU ProSun, had filed a subsidy complaint with the commission, which found it to be valid. Its investigation will last 13 months, although anti-subsidy duties can already be imposed after nine months if needed. The EU had launched another probe in September - also at the behest of EU ProSun - on whether Chinese solar panel producers are illegally undercutting prices on the European market. The EU is China's main export market.