Britney Spears has admitted she lost her virginity in high school years before she dated Justin Timberlake.

The Toxic singer, 41, made global headlines about whether she was a virgin while dating Timberlake, now 42, from 1999 to 2002 and famously declared in 2003 she had only had sex with “one person” in her “whole life”.

But in her upcoming memoir The Woman in Me, out October 24, the singer says she slept with her brother Bryan Spears’ childhood best friend when she was a freshman and he was a senior.

She does not name her teenage lover in the book, but she was dating a man named Donald “Reg” Jones at the time.

Spears told W magazine in 2003 about losing her virginity: “It was two years into my relationship with Justin. And I thought he was the one. But I was wrong.”

Referring to Timberlake then talking about their breakup and sex life on 20/20 in 2002, Spears added: “I didn’t think he was gonna go on Barbara Walters and sell me out.”

Britney Spears and then boyfriend Justin Timberlake in 2002. Photo / Getty Images

When she and Timberlake broke up in 2002, they went on to accuse each other of cheating.

Spears also uses her book to accuse Timberlake of cheating on her with two famous women – one of whom is thought to be All Saints singer Nicole Appleton.

The mum-of-two, whose husband Sam Asghari, 29, filed for divorce from her in August, also says in her upcoming memoir she aborted Timberlake’s baby while they were dating as he didn’t want to a be a dad at the time.

She said: “I loved Justin so much. I always expected us to have a family together one day. This would just be much earlier than I’d anticipated.

“But Justin definitely wasn’t happy about the pregnancy. He said we weren’t ready to have a baby in our lives, that we were way too young.”