David Cameron has resigned as prime minister after the UK public voted to leave the European Union in the referendum, Sky News reported.
Cameron - with his wife by his side - said he had already spoken to the Queen about his decision.
The PM campaigned to remain in the EU but the public rejected his arguments and chose to leave the EU by 51.9 percent to 48.1 percent.
Speaking to masses of reporters outside Downing Street, the PM said a new leader would be in place by the Tory party conference in October.
"The British people have voted to leave the European Union and their will must be respected," Cameron said.
He called it "an instruction that must be delivered" as he also thanked his supporters and congratulated Leave campaigners for their "spirited and passionate case".
The PM said he had fought "head, heart and soul" to stay in the union but that the British people had chosen a different path.