Ashley Tisdale "never thought" Zac Efron was hot.

The 37-year-old actress insisted she was never attracted to her 'High School Musical' co-star - who is two years her junior - because he was like a little "brother" to her.

Speaking on the 'Not Skinny But Not Fat' podcast, she said: "It's because I was friends with him before the movie. He was way younger than me. He was like a brother, too."

However, Ashley recalled she finally understand why so many girls had a crush on the 'Greatest Showman' star when he posed for Rolling Stone magazine in a white t-shirt in 2007.

She added: "I think the one time where I was like, 'Oh, OK. S***. Yeah, he looks hot,' was the Rolling Stone cover. I was like, 'Now I understand.'

"I think I just knew him too well and had been best friends with him for so long that it's like your brother that you're hanging out with."

The Frenshe founder previously admitted Zac was her worst on-screen kiss because of their close off-screen relationship.

She said: "I'll tell you why it was the worst, okay? I had to kiss Zac Efron on 'The Suite Life of Zack and Cody', and it's the worst because I am so close to him and he's like my brother.

"At the time, he was used to acting on like, Warner Brothers, which is CW, and we were on Disney Channel. And so he like, he tried kissing me with his tongue, and I was like, 'Get away from me!' I closed my mouth so fast.

"I was like, 'This is Disney Channel, we don't kiss like that on Disney Channel!'

"It's just weird when you're so close to somebody, and we'd already done the movie, I'd known him for years before. That is why it was the worst. It's just we're too close."