Gigi Hadid has posted a sweet birthday tribute to her brother Anwar.

Gigi and Anwar Hadid via Instagram (c)

Gigi and Anwar Hadid via Instagram (c)

The younger brother of the 22-year-old model celebrated his 18th birthday on Thursday (22.06.17), and Gigi took the time to post a touching tribute to her "amazing little brother" on her Instagram account to help him ring in his special day.

Posting a professional photograph of the pair during a photoshoot, Gigi wrote: "18 YEARS AGO MY LIFE WAS BLESSED W THE MOST SPECIAL AND AMAZING LITTLE BROTHER ON DA PLANET @anwarhadid you amaze me more every year- watching you grow and thrive in exactly who you are makes me more proud than you'll ever know. You inspire me and so many around you, and I feel so lucky to be your blood! HAPPY BIRTHDAY love you foreva (sic)"

The blonde beauty also posted a throwback picture of the pair on a toy bike, which was captioned: "ANWARCITO DAY part II (sic)"

Anwar's other sister and fellow model Bella Hadid, 20, also took to Instagram to post a series of photos of herself with her younger sibling, where she said she was "so proud" of her "best friend and favourite man".

She wrote: "Happy birthday my sweet angel. Your love and light is worth all of the stars in the sky! I'm so proud of the man you have become and are becoming. I'm so proud and lucky to call you my brother. Nobody loves you more than me my mini me @anwarhadid forever and ever and ever x infinity .. 18 years you're still my best friend and favorite man ! (sic)"

Meanwhile, Anwar also received an outpouring of love on social media from his mother Yolanda Hadid, who posted a sweet snap of the budding model as a baby on her own Instagram account.

She wrote: "Happy 18th Birthday my sweet angel, thank you for all the light you bring into my life, you inspire me to be the higher me. Your kindness and consciousness is the greatest gift I treasure everyday so thank you for all that you do and all that you are to me and your sisters...... #loveYou#AlwaysAndForever #June22 (sic)"