Surprising the birthday girl on Saturday night at Restaurant Nora in Washington's Dupont Circle neighbourhood were her mother Marian Robinson and friends, including Attorney General Eric Holder, White House Adviser Valerie Jarrett and Jocelyn Frye, who is a domestic policy adviser to both the president and first lady.

Mrs Obama walked into the restaurant in a dark, knee-length frock. President Obama was dressed casually with no tie.

Michelle Obama will turn 46 on Sunday but her husband is expected to be in Massachusetts campaigning for Martha Coakley, who is in a tough fight with Scott Brown to replace the late Senator Edward Kennedy and retain the Democratic party's 60-vote majority in the US Senate.

She spent part of her last birthday on a train from Philadelphia to Washington, as her husband made his way to the Capitol to be inaugurated.
Restaurant Nora claims to be a pioneering organic restaurant, with 95 per cent of its food produced by organic growers since 1999.