One Direction
The clip is an outtake from the band's appearance on the show earlier this year. YouTube

They are accustomed to belting out pop songs and ballads but One Direction went back to basics during a recent appearance on Sesame Street.

A video posted online shows band members Harry Styles and Liam Payne treating their young fans to a musical rendition of the alphabet with the help of an unlikely star, Sesame Street's Bert.

The newly-released footage, which appears to be an outtake from the boyband's appearance on the show early this year, has gone down a treat with fans.

"This is so cute how they did a little song for the little kids on Sesame Street is so adorable I love the last part when Louis was singing it was so cute he sounds really good," one fan said.

Another wrote: "I'm showing this to my future children "

When the boy band visited the street in January they reworked their hit What Makes You Beautiful for a new letter-focused tune called What Makes U Useful, which emphasised the importance of the vowel 'U'.

They are the latest stars to make a cameo on the iconic kids' PSB show in recent months.

Benedict Cumberbatch performed with Count Von Count and Murray-arty when he appeared on the show and Mad Men's Jon Hamm has also visited the street this year.