By Valerie Volcovici WASHINGTON (Reuters) – Oil and gas producer ConocoPhillips on Friday said it would support a UN climate change agreement if it met its own policy principles, including creating a “level playing among energy sources and between countries.” The comments by the Houston-based company were a clarification of its position on the proposed UN agreement after it earlier in the week answered ‘yes’ to a question in a climate change survey that asked whether it backed a 2015 UN accord. The company’s partial endorsement comes as pressure grows on U.S. oil majors to follow the lead of European counterparts who backed the UN climate negotiation process and called for a global carbon pricing system to tackle carbon emissions.