(File image) Britney Spears

London - Britney Spears is “excited” about her sister's engagement.

The 31-year-old singer is thrilled at the news her younger sister, Jamie-Lynne Spears, is going to marry her boyfriend of three years, Jamie Watson, and the newly-brunette beauty shared her congratulations on Twitter.

Britney posted: “So excited and happy for my sister, congrats @jamielynnspears - love you. (sic)”

Jamie, 21, revealed her happy news on Sunday by posting an Instagram photo of her dazzling diamond engagement.

Referring to her fiance's gesture, she wrote: “He did good! (sic)”

This is the actress and singer's second engagement after she was previously set to walk the aisle with her on/off boyfriend of five years Casey Aldridge, the father of her four-year-old daughter Maddie, before they split up in February 2010.

Jamie's happy news comes shortly after her sister Britney - who has sons Sean Preston, 7, and Jayden James, 6, from her marriage to Kevin Federline - split from her fiance of 13 months Jason Trawick in January and she recently admitted she will “always love” the talent agent.

She said: “Jason and I have decided to call off our engagement. I'll always adore him and we will remain great friends.” - Bang Showbiz