Washington, July 27 (ANI): Britney Spears has left estranged hubby Kevin Federline livid by taking their sons for an impromptu trip to the gambling capital of the world Las Vegas.

The pop star, who has been in the news for the past few days for a disastrous interview that she gave OK! Magazine, was accompanied by her brother Bryan when she flew to Sin City on Wednesday, July 25th with sons Sean Preston and Jayden James.

Britney, who told OK! that Federline was trying to get sole custody of their sons, may find herself in deeper trouble with not only him, but also the law, for under California law, neither parent is allowed to take a child out of state without written permission from the other.

They can only take kids without permission if they have obtained a court order.

According to a source, K-Fed is now demanding that Britney, who failed to notify him or his attorney, Mark Vincent Kaplan, bring the kids back.

"K-Fed is demanding that she get back to Los Angeles because she isn't allowed to have the kids out of state," Us Weekly quoted the source, as saying.

Another Federline source reveals that Federline's lawyer is now mulling over what action to take.

"Britney did not have written permission to take the kids out of state. She needs written permission and she never got it or alerted people she was leaving. I'm sure Kevin's lawyer, Mark Vincent Kaplan, is mulling over how to handle this," the source said.

A lawyer for Spears did not respond to calls for comment.

Britney's decision to take her kids away will only increase fears that she is nearing a breakdown once again, especially after the interview she gave OK! magazine.

The singer had earlier personally called the magazine to ask bosses whether they would like to include an interview with her in their new issue.

She apparently not only wanted to set the record straight about her numerous problems including the feud with her mom, Lynne Spears, and her divorce with her estranged husband, Kevin Federline, but also her stint in rehab.

However, things went horribly wrong when she shocked OK! staff by not only making frequent toilet breaks, talking in baby talk and more shockingly vomiting all over her Gucci dress, but also walking off with thousands of dollars of merchandise.

Spears allegedly fled the shoot wearing 12,861 dollars worth of jewelry, a 974 dollar Vera Wang dress, 380 dollars Lanvin heels and a 281 dollars Pucci scarf.

Britney also caused thousands of dollars worth of damage, including a Versace gown, Alisha Levine dress, Marnie heels and the 6,700 dollar Zac Posen gown her dog pooped over.

When the clothes she ruined are added, the total comes to 21,267 dollars. (ANI)