Britney Spears' pregnant 16-year-old sister Jamie Lynn is engaged, it has been reported.

People magazine today reported Jamie - the star of television show Zoey 101 - has been showing off an engagement ring to friends.

"She's got an engagement ring," People quoted a source as saying.

"She's been showing it off, talking about it."                                                                                                               

People reported Jamie's fiance is the father of her baby, Casey Aldridge.

Jamie caused controversy and sparked nationwide debate when she announced her pregnancy last year.

Afterwards, Jamie's mother Lynne cancelled plans to release a parenting book.

Her sister, pop star Britney, regularly hits tabloid headlines for her erratic behaviour, although she seems to have calmed down of late.// Stuff.co.nz