BEIJING — China said Monday it provided an equal playing field for domestic and foreign companies bidding for environmental projects in its lucrative green sector, amid concerns it favors local firms. “We use an open bidding process … to ensure the implementation of projects,” Jiang Yaoping, vice commerce minister, told reporters in response to a question about foreign investment into green industries. “These measures have provided companies, including foreign-invested firms, with a chance to participate in a fair way,” he said, adding the government maintained a policy of treating domestic and foreign firms equally.Beijing has pledged to spend US$738 billion developing clean energy over the next decade as it seeks to meet a target of generating 15 percent of its energy from renewable sources — mainly wind and water — by 2020. The nation’s vast market and deep pockets are attracting a growing number of foreign companies which face severe challenges in their home markets due to the global financial crisis. At the same time, Beijing has faced a growing chorus of accusations by foreign companies, business groups and governments that overseas enterprises are encountering an increasingly skewed playing field in the country. A row has also erupted between China and the United States over the impact of Beijing’s subsidies on its renewable energy sector, with claims foreign firms are excluded from receiving government help in the Asian nation. The U.S. Department of Commerce announced in September it was investigating whether China’s support for its domestic renewable energy companies broke international trade rules. But China’s Ministry of Commerce has dismissed claims it is unfairly supporting its green-technology industry.