Mariah Carey has been trying out so many Halloween costumes on her twins it's like the tots are 'prepping for a tour'.

The American singer and her husband Nick Cannon welcomed daughter Monroe and son Moroccan Scott into the world in April.

Halloween is Mariah's favourite holiday and she's looking forward to spending it with her children for the first time. She is keen to ensure they look their best, so has been testing different looks out.

'She's been dressing them up and sending me tons of pictures. It's like they're prepping for a tour!' Nick was overheard joking, according to New York Post.

Mariah is apparently 'so excited' about the spooky day, she's gone slightly overboard with costumes. She's bought the twins so many options she had to organise extra closet space at her New York home to store them.

The star has apparently had another wardrobe built just to house the outfits.

Mariah and Nick recently shot an interview with Barbara Walters in which they introduce Monroe and Moroccan Scott to their fans. It's for show 20/20 and will hit screens in the US on October 21.

'Mariah and Nick recently sat down with Barbara Walters in their New York apartment to discuss Mariah's pregnancy, their marriage, their beautiful baby twins Monroe and Moroccan and much more,' the singer explained on her website.