Kevin Federline is reportedly urging estranged wife Britney Spears to go into rehab for her own sake as well as for their children.

A source close to Kevin has told Star magazine that Kevin is worried about her after seeing her constant partying since their split in November.

The source said: "Kevin has tried to convince Britney to check herself into rehab from every possible angle. First he tried threatening to take away the kids, then he tried pleading with her to take care of herself."

According to the source, Kevin has even teamed up with his former mother-in-law Lynne to get Britney to pull herself together: "He's afraid she's going to hurt herself."

"[Their sons] being raised by strangers. He told Britney to get help before it's too late."