More than two dozen world leaders will join President Barack Obama in an extraordinary weekend of back-to-back summits to tackle Europe's mounting economic woes and solidify plans for winding down the decade-long war in Afghanistan.

Barack Obama will host the G8 summit at his Camp David presidential retreat in the Maryland countryside instead of Chicago as first scheduled, the White House said.

President George Bush and Russian President Vladimir Putin today urged Iran and North Korea to abandon suspected nuclear weapons programmes, glossing over divisions about how to deal with both countries.

United States President George W Bush transferred his leadership powers to Vice President Dick Cheney for more than two hours today while he went under sedation for a routine colon screening.