Kevin Federline's uncle dies

Kevin Federline's uncle passed away Friday after losing his lengthy battle with cancer, sources confirm.

Federline -- the ex-husband of Britney Spears -- had recently visited Steve, his mother's brother, who lived in Fresno, CA.

"The whole family is very sad but at least he is out of his pain now," the source told Us Weekly magazine.

Federline celebrated his 30th birthday in Las Vegas last Friday night, dining at Social House and then hitting up club PURE with 20 pals, including ex Shar Jackson.

On turning 30, K-Fed said, "Ugh [it's] horrible!"