The actor revealed he saw "some sparks" while the trio was filming the Harry Potter series

Rupert Grint is opening up about the close relationship between his Harry Potter costars Emma Watson and Tom Felton.

“There was always something. There was a little bit of a spark,” Grint, 31, told Entertainment Tonight about Watson and Felton while promoting his AppleTV+ series The Servant.

Although Grint said he didn’t want to stir any rumors, he did say he saw “some sparks” while the trio was filming the Harry Potter series.

“But we were kids. It was like any kind of playground romance,” he said, jokingly adding, “I didn’t have any sparks. I was spark-free.”

Tom Felton, Emma Watson
Tom Felton and Emma Watson
| Credit: D Dipasupil/FilmMagic

Reps for Felton and Watson did not immediately respond to PEOPLE’s request for comment.

Grint’s comments come after the Little Women actress, 29, spoke about being single while gracing the December cover of British Vogue.

“I never believed the whole ‘I’m happy single’ spiel,” Watson said. “I was like, ‘This is totally spiel.’ It took me a long time, but I’m very happy [being single]. I call it being self-partnered.”

Felton, 32, praised Watson while speaking to MailOnline, saying, “I like it! It’s the first I’ve heard of [the term] but it’s great.”

Rupert Grint, Emma Watson and Tom Felton
Rupert Grint, Emma Watson and Tom Felton
| Credit: Dave Hogan/Getty Images

He continued, “I’m in the same category, to be honest with you, quite happily self-partnered.”

“I think in this day and age it’s not a necessity to be with someone just for the sake of being with someone, so I like the idea of self-partnering,” Felton added. “I think you need to love yourself before you can love anyone else, so that’s a start.”

Felton and Watson often share photographs of each other on Instagram when they’re hanging out, whether it’s at the beach or when Felton is teaching the actress how to play guitar.

“It’s always nice to bump into her, see her at the beach, or over dinner or whatever,” he said. “She’s an incredibly smart and lovely young lady, so it’s always nice to bump into each other and slightly reminisce about old times but also about looking forward to the future.”