WASHINGTON, Nov 12 (Reuters) - President Barack Obama and British Prime Minister David Cameron spoke on Tuesday about their expectations for the next round of negotiations on Iran's nuclear program, part of a phone conversation about several security issues in the Middle East, the White House said.

"On Iran, the president and prime minister reiterated their support for the P5+1's unified proposal and discussed their expectations for the next round of talks," the White House said, referring to the group of major world powers that are negotiating with Tehran. (Reporting by Roberta Rampton and Steve Holland; Editing by Eric Walsh)