SHANGHAI, Sept 17 - Heavily subsidised U.S. farmers are dumping soybeans on the Chinese market, a government researcher said on Thursday, adding heat to a simmering trade row between the two countries.

Chen Dongqi, vice-head of the macroeconomic institute of the National Development and Reform Commission, suggested the United States was guilty of double standards after slapping a 35-percent tariff on China-produced tyres this week.

"The U.S. government gives large amounts of subsidies to its farmers and dumps soybeans in China," he told a conference.

China imported a record 29.9 million tonnes of soybeans in the first eight months of the year, around 40 percent of which originated in the United States.

Chen said the decision by the Obama administration to impose added duties on Chinese tyre makers was a sign of growing U.S. protectionism and "could restrain global demand and cut international trade".

Amid concerns that growing protectionism could scupper economic recovery, trade ministers gathered in India earlier this month as part of an effort to "re-energise" Doha trade talks, now in their eighth year.

Beijing said it would challenge the tyre tariff at the World Trade Organisation, and Premier Wen Jiabao vowed in a speech last week that China would "fight resolutely" against all kinds of protectionism.

However, the risk of tit-for-tat measures remains, with China already launching new anti-dumping investigations against U.S. poultry and auto product imports.