Spears was said to have worn jeans to her wedding

The singer married Jason Alexander on Saturday morning, during a night out in Las Vegas.

But immediately her lawyers filed for an annulment by the courts.

"Plaintiff Spears lacked understanding of her actions to the extent that she was incapable of agreeing to the marriage," the annulment petition said.

It was just crazy, man

Jason Alexander on his short marriage

"Jason agreed to this completely. They've made a wise decision. I know they care about each other. They are friends," he added.

Wild and crazy

But Mr Chesnoff denied Spears was intoxicated when she went through with the ceremony at the Little White Wedding Chapel in Las Vegas.

Ex-husband Alexander has now spoken about the surprise wedding.

"It was just crazy, man," he told Access Hollywood.

"We were just looking at each other and said, 'Let's do something wild, crazy. Let's go get married, just for the hell of it'."

He added that they soon realised that they had to fix the "mistake" they had made.

An annulment dissolves a marriage as if it never took place, while a divorce would have recognised that it did occur.

Court information officer Michael Sommermeyer read out the reasons why the annulment was sought.

"Before entering into the marriage the plaintiff and defendant did not know each other's likes and dislikes, each other's desires to have or not have children, and each other's desires as to state of residency.

"Upon learning of each other's desires, they are so incompatible that there was a want of understanding of each other's actions in entering into this marriage."

Joke too far

Spears record company said that the wedding had been a joke that had gone too far.

Spears and Alexander, both 22, grew up together in Louisiana.

For the ceremony at the famous Las Vegas chapel, the singer wore jeans and baseball cap.

Spears once said she would remain a virgin until she got married, making her a role model for the pro-chastity movement in the United States.

Lawyer David Chesnoff was quick to file for an annulment

Her fourth album, In the Zone, was released in November.

It was not well received by critics but it went straight in at the top of the Billboard 200 album chart.

Since 1999, the singer has sold more than 54 million albums around the world.