Brown told Obama in a phone call Tuesday that he will send Foreign Secretary David Miliband to represent Britain at the April 12-13 meeting. Obama is hosting dozens of world leaders to discuss the spread of atomic weapons and the threat of nuclear terrorism.

Earlier Tuesday, Brown announced a national election will be held May 6. His Labour Party is seeking a fourth term in office but the opposition Conservatives are ahead in the polls and favored to take power for the first time since 1997.