The Environmental Protection Agency has said that it requires more time to study data on forming rules governing emissions of green house gasses from power plants.

The agency, however, pointed out that the move will not delay the implementation of the final rules in 2012. It is expected to propose the greenhouse rules by Sept. 30 in places of July 26 and finalize the rules by 2012.

"A wide range of stakeholders has presented the agency with important input which deserves to be fully considered as the agency works to develop smart, cost-effective and protective standards," EPA spokeswoman Cathy Milbourn said in a statement.

On the other hand, the agency is also working on preparing greenhouse-gas standards for petroleum refineries and will propose them in December this year. EPA was swung into action after it was sued by several states, local governments and environmental groups over its failure to update its rules to govern the sectors, which are among the biggest sources of greenhouse gases.