Several big Chinese companies were forced to delay initial public offerings last year to comply with environmental rules, the State Environmental Protection Administration said, underlining the importance of financial levers for the agency as it struggles to rein in pollution.

Ten domestic IPOs - including one by China Coal Energy, the country's second-largest coal producer by output - were held back in the second half of 2007, after the Government began vetting such deals for environmental factors, Sepa said. While most of those offerings were later approved, two companies, including Zijin Mining Group, still haven't won approval, Sepa said.