Britney Spears begged Kevin Federline to come to her birthday party

Troubled pop princess Britney Spears reportedly begged her ex-husband Kevin Federline to join her in celebrating her 26th birthday on Sunday.

According to reports, the 'Gimme More' singer was seemingly happy as she partied 'till 4am with pal Paris Hilton - but then made a late-night call to Federline, 29 - pleading with him to join her.

A source close to Spears said: "She begged him to come out with her. Kevin reminded her that one of them needed to be a parent and take care of the boys. Then she hung up on him. Kevin said she was drinking."

Meanwhile, Britney was almost replaced in her music video for new single 'Pieces of Me'.

Bosses at Britney's record company Jive were said to be furious after she failed to show up for the shoot - and threatened to hand over the $500,000 set to one of their upcoming stars to use for her own video.

A Jive Records insider said: "Britney was supposed to shoot a video for her song 'Pieces of Me' last week. Jive hired Wayne Isham to direct, had all the dancers there - hair, make-up and everything. But she refused to come. Jive was really upset.

"They were going to use it for another Jive artist, Samantha Jade, because it was too expensive to just scrap. But Britney finally showed up 12 hours late when she realised a new, younger, hotter girl would take her slot."