Meeting the Queen: the Queen's senior aides have called emergency meeting at Buckingham Palace. Image: Getty

And no one knows why ...

The entire royal staff of Queen Elizabeth has reportedly been called to an emergency meeting at Buckingham Palace this morning.

Workers from as far as Balmoral, Scotland have been called back to London where Lord Chamberlain, the highest officer of the household and the Queen's right-hand man, Private Secretary Sir Christopher Geidt, will address the meeting this morning, according to Daily Mail.

However, royal sources are now playing down the urgent meeting as "not unusual", despite the news sending global media into a frenzy.

The urgent summit has fueled speculation of a major royal announcement, including that it is related to either the Queen or her husband the Duke of Edinburgh’s health. News trucks have now been gathered outside the palace for hours awaiting any word.

Canadian broadcaster Rosa Hwang tweeted earlier Buckingham Palace press office had confirmed to her that both the Queen and Prince Philip were "alive and well".

More details are expected at 8am today (5pm AEST).

READ MORE: What will happen when the queen dies The Queen was last seen on May 3. Photo: Lauren Hurley/PA Wire.

Royal staff meetings are not unusual — but this time staff have been summoned 'at the eleventh hour', reports Daily Mail. Multiple sources have said a last-minute meeting is 'highly unusual' and 'everyone is on tenterhooks,' said one source.

"Although meetings involving the entire royal household are occasionally called, the way this has been done at the eleventh hour is highly unusual and suggests that there is something major to be disseminated." The Queen was last seen on May 3. Photo: Lauren Hurley/PA Wire.

"But at the moment, only those closest to her genuinely know what on earth this is all about," the source added.

The Queen was last seen on May 3 arriving at Buckingham Palace ahead of an audience with Prime Minister Theresa May to mark the dissolution of Parliament for the General Election.

Her husband, Duke of Edinburgh Prince Philip, was seen yesterday opening the new Warner Stand at Lord's Cricket Ground in London.

Queen Elizabeth recently returned to her London residence following her Easter holiday at Windsor. She turned 91 last month while Prince Philip will celebrate his 96th birthday in June.

Buckingham Palace declined to comment on the reason for the meeting last night.