U.N. climate talks opened on Monday, exposing familiar rifts between rich and poor countries which delegates said were likely to delay a re-start of formal negotiations. The 185-nation Bonn conference, which will run until June 11, is the biggest international meeting on climate change since a summit last December in Copenhagen failed to agree a new pact. Several countries said they could not give a green light to formal negotiations on a new text published in mid-May and which outlines a huge range of options for fighting climate change. The Copenhagen summit last year struggled to overcome suspicion on how to share global effort to curb greenhouse gases under a new deal to succeed the Kyoto Protocol after 2012. On Monday differences re-emerged when a clutch of Latin American countries said they could not start negotiations on the new text.