BONN, Germany - The United Nations says formal negotiations on an international treaty to control global warming will resume in Bonn in April, four months after the failed climate change summit in Copenhagen.

UN climate chief Yvo de Boer said Tuesday the negotiating schedule is being intensified in order to secure a global climate deal at the end of the year. After the Bonn meeting April 9-11, more talks are scheduled there for May 31-June 11.

The next world climate summit is to take place in Cancun, Mexico, from Nov. 29 to Dec. 10.

De Boer, who will resign July 1, said that since Copenhagen 100 countries have submitted individual emission cut targets. He said he saw commitment by governments "to move negotiations forward toward success in Cancun."