AMSTERDAM (AP) -Top U.N. climate-change official Yvo de Boer tells The Associated Press says he is resigning after nearly four years.
Governments struggled without success to agree on a new global warming deal during his term.
His resignation takes effect July 1, five months before 193 nations are due to reconvene in Mexico for another attempt to reach a worldwide agreement on controlling greenhouse gases.
De Boer told the AP on Thursday he believes talks on a new treaty are on track, despite the frustration of failing to reach a deal at the Copenhagen climate summit in December.
De Boer said he had begun looking for another job before Copenhagen and his decision was unrelated to the summit's outcome.