Hillary Clinton claims historic victory as Democratic nominee

Bernie Sanders has said he was "really disappointed" that rival Hillary Clinton was declared the presumptive Democratic nominee on the eve of primary elections in six states, by the Associated Press.

Mr Sanders expressed concern that the reports of Mrs Clinton's victory came the night before California which he described as "the largest primary" - and was annoyed by the way it was done.

He said that it was based on what he described as "anonymous" commitments from superdelegates - the party insiders and Democratic officials who can vote for the candidate of their choice at the summer convention.

President Barack Obama has congratulated Hillary Clinton on securing the delegates needed to become the Democratic presidential nominee.

"Her historic campaign inspired millions and is an extension of her lifelong fight for middle-class families and children," White House spokesman Josh Earnest said in a statement.

Mr Obama also spoke to Clinton's rival Bernie Sanders and will meet with him on Thursday at Sanders' request, Earnest said.

"The president thanked Senator Sanders for energising millions of Americans with his commitment to issues like fighting economic inequality and special interests' influence on our politics," the White House said.