Kim Kardashian is "so excited" to be an aunt for the second time.

The 31-year-old star's sister Kourtney Kardashian gave birth to her second child, a daughter named Penelope Scotland Disick, on Sunday (08.07.12) and she is delighted to have an extra addition to the family, and a younger sister for two-year-old Mason.

Writing on twitter, she said: "Kourtney gave birth to a beautiful baby daughter on Sunday and the whole family is so thrilled to finally meet her! She is absolutely perfect! I am so excited to be an aunt again and can't wait to spoil little Penelope. I know Mason is going to be the best big brother in the whole world. Congratulations Kourtney and Scott. Xo (sic)"

Kourtney - who had the baby naturally at the Cedars-Sinai Medical Center in Los Angeles - said she was "resting comfortably" since the birth.

She said in a statement: "Scott and I look forward to welcoming you very much, our little angel Penelope Scotland Disick. We are blessed. Mommy and baby are resting comfortably."

Her mother Kris Jenner added the young tot looks similar to her older brother.

She said: "It was a great. She had an easy delivery. Penelope is so cute. She looks just like Mason. She's so beautiful. We are so happy."