Lady GaGa is reportedly coaching her sister to become a pop star.

The 'Telephone' singer - real name Stefani Germanotta - has reportedly put her 17-year-old sibling NatAli Germanotta in touch with a top New York vocal coach with a view to training her as a backing singer.

Natali has also been sitting in on her sister's studio sessions to learn about songwriting and recording.

A source said: "Natali idolises her sister so of course she wants to follow in her footsteps.

"She's spending a lot of time with her and sitting in on recordings. She's got the bug.

"She has also taken to a playlist of Gaga's favourite tunes and is tapping into her influences to fit in with her vocal style."

The teenager's parents are adamant, however, that she has to finish school this year before embarking on a music career.

Natali appears in her sister's latest music video, nine-minute epic 'Telephone'.

The teenager plays one of the women put in prison with Gaga, who is subsequently broken out of jail by Beyonce Knowles.

Beyonce's sister Solange also followed her into the music business and has so far released two albums.