Mariah Carey decided to release a new Christmas album because she was unhappy with her first effort.

The 'All I Want for Christmas Is You' singer - who is currently pregnant with twins, her first children with husband Nick Cannon - says she wanted to release 'Merry Christmas II You' because she can't listen to her first festive release 'Merry Christmas', which came out in 1994, without being critical of it.

She said: "'Merry Christmas II You' is like the sequel to my first Christmas album. Every Christmas, I listen to it and I love certain songs, but on some of them I'm like, 'I hate this vocal performance'. So I decided to do this album."

The 41-year-old pop star is due to give birth to her babies in spring 2011 but she still intends to release an LP next year.

She told Britain's HELLO! magazine: "I'll start writing songs at some point soon, because that's a creative process and I think this is a creative time in my life."