Beijing said that duties imposed on US poultry exports were lawful, after Washington asked the World Trade Organization to look at Chinese tariffs on the billion-dollar chicken trade. The commerce ministry on Wednesday said anti-dumping and anti-subsidy tariffs were in line with WTO rules, after the United States opened a fresh front in the fight for better access to Chinese markets. "China will carefully study the consultation request raised by the US and appropriately deal with the issue in accordance with WTO dispute settlement procedures," the ministry said in a statement. The US move is the first step towards possible sanctions in the one-year-old dispute and is just the latest in a series of trade spats between the world's two largest economies. US government lawyers estimate the duties hit 90 percent of exporters in the sector, obliterating a market that had been worth around $1 billion before duties were announced in September 2010. As the United States struggles to recover jobs lost during the global financial crisis, many American lawmakers blame Chinese trade and currency policies for the country's economic woes. US Trade Representative Ron Kirk Tuesday called on China to "play by the rules", branding the series of Chinese duties on US chicken exports as "inconsistent" with WTO regulations