Ananova:

Britney Spears' "joke" wedding to a childhood friend has officially been annulled.

The singer wed Jason Allen Alexander on the Las Vegas Strip in the early hours of Saturday. But within hours the 22-year-old star realised she had taken the "joke too far", according to a spokesman.

Prominent Las Vegas lawyer David Chesnoff said that he filed the complaint for annulment in the Family Court at 10.12am.

"There are grounds for this court to grant an annulment because plaintiff Spears lacked understanding of her actions to the extent that she was incapable of agreeing to the marriage," the annulment papers said.

Spears' record label, Jive, said in a statement: "On January 3, Britney Spears and a friend took a joke too far by getting married. Ms Spears and Mr Alexander have filed for an annulment which will become official on Monday, January 5."

The ceremony was reportedly videotaped and Spears is said to have shown the footage to friends. The Las Vegas Sun reported that the Little White Wedding Chapel, where Spears said "I do", has been offered hundreds of thousands of pounds by newspapers for a copy of the tape.

Spears and Alexander apparently planned their rushed wedding on Friday night as they partied at the Ghostbar, part of the Palms Casino Hotel in Las Vegas. They were driven to the Little White Wedding Chapel, where Dixie Chick Natalie Maines, and film stars Bruce Willis and Demi Moore have also tied the knot.

When they were told they needed a licence they were driven to the Clark County Marriage Bureau office at the downtown Las Vegas courthouse. Documents filed early on Saturday with the Clark County marriage bureau showed that Spears, of Kentwood, Louisiana, and Jason Allen Alexander, also of Kentwood, were granted a marriage licence.

The "honeymoon" took place back at a luxury suite at the Palms hotel immediately after the wedding.