Lin-Manuel Miranda has promised the live-action 'Little Mermaid' will still feature the classic songs from the original animated movie.

The 42-year-old star is working with composer Alan Menken on some new tracks for the upcoming film but he has reassured fans they won't take the place of the likes of 'Under the Sea' and 'Part of Your World'.

He told Variety's 'Awards Circuit' podcast: "We wrote three or four original tunes, replacing none of the ones you like. All of those are in.

"There's no bigger Little Mermaid fan than me.

"But we found a couple of opportunities for some other music that I can't wait to see. I'm in the dark as anyone else, honestly."

Of the new songs, the 'Hamilton' creator revealed one comes when Halle Bailey's Ariel gives up her voice to become a human.

He said: "[Director] Rob [Marshall] found a creative way to hear from Ariel, even though she is sans voice for a little while. We wrote some music [for] her time on land. She experiences a lot of firsts, as someone with legs for the first time, so we got to lean into all of that musically."

But Melissa McCarthy's Ursula won't have anything new to sing, though Lin wouldn't rule out the possibility of Daveed Diggs showing off his rapping skills as Sebastian.

Lin has enjoyed collaborating with veteran composer Alan on the project.

He said: "Alan will tell you if he does not like something.

"He's a very like heart and opinion on sleeve guy. ... He's scoring it as well, along with the songs, just as he did with the original.

"I won’t see a rough cut for another month or couple of months, but the fact that he’s excited has me excited."