Jennette McCurdy explains why she was jealous of co-star Ariana Grande

Jennette McCurdy has revealed why she was jealous of her former co-star Ariana Grande.

The former Nickelodeon star, 30, has written candidly about her relationship with Grande, 29, in her new memoir, I’m Glad My Mom Died.

McCurdy and Grande starred in the comedy series Sam & Cat together, a spin-off uniting their characters from iCarly and Victorious respectively.

The series aired for only one season between 2013 and 2014.

Nickelodeon.

During this time Grande’s pop career took off and she released a string of hits. In her book, McCurdy explains that she often had to ‘angrily hold down the fort’ while Grande ‘regularly’ missed filming ‘to go sing at award shows, record new songs and do press for her upcoming album’.

The former child star ultimately felt that she was treated unfairly in comparison to the ‘Break Free’ singer and she did not understand why Grande was ‘allowed to’.

“I booked two features during iCarly that I had to turn down because the iCarly team wouldn’t write me out of episodes to go shoot them, McCurdy claims about her role on the hit Nickelodeon sitcom.

AFF / Alamy Stock Photo.

She goes on to say that initially Grande missed the occasional day on set but she was then told that her co-star would miss a whole week of filming.

“The week where I was told Ariana would not be here at all, and that they would write around her absence this episode by having her character be locked in a box. Are you. Kidding me," she writes.

"So I have to turn down movies while Ariana’s off whistle-toning at the Billboard Music Awards? F**k. This”.

McCurdy, who has since retired from acting, also reveals her feelings of resentment towards Grande because her character Sam Puckett was meant to have her own spin-off.

Pictorial Press Ltd / Alamy Stock Photo.

She writes: “This was supposed to be Just Puckett, the harrowing tale of a brassy juvenile delinquent-turned-school counsellor. Now it’s some half-baked two-hander -- Sam & Cat -- about a brassy juvenile delinquent who, with her 'ditzy best friend,' starts a babysitting company called 'Sam & Cat’s Super Rockin’ Fun-Time Babysitting Service'. This is not harrowing.”

The book has made headlines this week after the podcaster revealed her shocking experience working on shows as a young actor and detailed the constant control of her mother, Debra McCurdy, who died in 2013 from cancer.

McCurdy’s mother allegedly controlled her career, her meals, and even supervised the actor's showers The former actor also says her mum administered breast and vaginal examinations and shaved her daughter's legs.

I'm Glad My Mom Died is out now.