This much is known: About 7:15 Tuesday night, a glittering blonde, decked out in a red and gold sari, holding the hand of her black-tuxedoed-escort, swept past the camera crews and reporters camped out to catch the red-carpet arrivals for the first state dinner given by President Barack Obama.

"Hey, that's a 'Desperate Housewife'!" one reporter yelled out.

In fact, the couple - Michaele Salahi and her husband, Tarek - are Virginians who have been auditioning for a possible role in a different housewives franchise: the TV program "The Real Housewives of Washington."

They swept past the camera crews and followed the trail of other bigwigs attending the dinner.

But neither Mr or Mrs Salahi, best known in the Washington area for promoting wine and polo in Virginia, were on the guest list for the event, a fact first reported Wednesday morning on the Washington Post Web site.

A White House official confirmed Wednesday that the Salahis were not invited nor were they seated for dinner in the tent erected for the evening. It was not clear Wednesday night how close the Salahis got to Obama and his wife, Michelle, or to the guest of honour, Prime Minister Manmohan Singh of India, and his wife, Gursharan Kaur.

Edwin M Donovan, a spokesman for the Secret Service, said Wednesday night that "initial findings identified a Secret Service checkpoint which did not follow proper procedures" allowing the couple to get access to the festivities, even though their names were not on the invitation list.

He declined to offer any more details, including what kind of procedures were not followed, why they were not followed and whether the couple has been interviewed. He said the investigation was ongoing.

"The bottom line is that they should not have gotten in," Donovan said.

He also said that he was unaware of any other examples of this kind of party-crashing at the White House. "I'm not aware of any other incidents like this," Donovan said.

The Salahis posted photographs of themselves at the dinner on their Facebook page: "Honoured to be at the White House for the state dinner in honour of India with President Obama and our First Lady!"