Washington, Muharram 13, 1438, Oct 14, 2016, SPA -- Countries may sign up to different deadlines for phasing out greenhouse gases used in refrigerators and air conditioners, a U.S. official said on Friday during a summit in Rwanda of some 150 nations meeting to strike an environmental pact. Jennifer Haverkamp, the U.S. Special Representative for Environment and Water Resources, told Reuters that countries may agree separate timelines for phasing out factory-made hydrofluorocarbon (HFC) gases, which can be 10,000 times more powerful than carbon dioxide as greenhouse gases, Reuters reported. "It's quite possible that there will be a couple of different groups that countries can slot into, depending on what level of ambition they are able to take on," she said. -- SPA 19:42 LOCAL TIME 16:42 GMT www.spa.gov.sa/w