SAN FRANCISCO, June 23 - U.S. President Barack Obama was briefed by his advisers late on Thursday on Britain's vote to leave the European Union, a result that he had argued passionately against during an April visit to London.

Obama, who was scheduled to deliver remarks to global entrepreneurs at a conference at Stanford University at 10:45 am PDT (1:45 p.m. ET/1745 GMT), was dining out at an upscale restaurant with a small group of top venture capitalists and Silicon Valley entrepreneurs as the results for the "leave" campaign began to roll in.

The group at San Francisco's Twenty-Five Lusk included John Doerr of Kleiner Perkins Caufield Byers, and LinkedIn's Reid Hoffman.

Obama dined for more than two hours, departing shortly after British networks called the referendum for the "leave" campaign, and markets plunged. A White House official said Obama had been briefed on the returns and would "continue to be updated by his team as the situation warrants."

"We expect the president will have an opportunity to speak to Prime Minister Cameron over the course of the next day, and we will release further comment as soon as appropriate," the official said in a brief statement to reporters.

Obama traveled to London in April at the request of Cameron, who he calls a friend, exhorting Britons to stay in the EU, an unusual intervention that was denounced as meddling by those in the "leave" campaign.

Obama also warned that leaving the EU would put Britain at the "back of the queue" for a trade deal with the United States.

Obama's term in the White House ends Jan. 20, 2017. His former Secretary of State Hillary Clinton, the presumptive Democratic candidate in the Nov. 8 election, had also said she hoped the UK would stay in the EU.

The presumptive Republican nominee in the Nov. 8 election - real estate magnate Donald Trump - had taken the opposite stance, saying he thought the UK should leave. Trump, in Scotland to reopen a golf resort, was slated to give a news conference on the 9th hole at noon (7 a.m. ET/1100 GMT).