As movie offers go, it must be hard to turn down one from Mr Kermit T Frog. This is how Amy Adams, the three-time Oscar nominee, found herself starring alongside the Muppets in their latest film outing, cunningly also called The Muppets.

"Kermit was a big part of my decision," Adams admits. "I don't think a lot of people get a personalised video message from Kermit the Frog, and now I have that forever!

"I wanted to be part of the movie, and I knew it would touch other people because if I had that reaction with Kermit just saying my name, the Muppets hadn't gone anywhere."

Kermit, dressed today in his distinctive green felt, adds: "I admire her. I think she's a fantastic actress in just about everything I've seen her do.

"Jason [Segel] and I recorded many solicitations to big stars and Amy's the only one that called back."

Last seen on the big screen in 1999's Muppets From Space, Kermit, Miss Piggy and co, who in their TV show heyday of the late Seventies got viewers shouting Mah-na Mah-na, may have waned in popularity compared to the hi-tech likes of the Transformers and Teenage Mutant Ninja Turtles. But the new movie looks set to propel them into the spotlight again.

Long-time Muppet fan Segel, star of comedies such as Knocked Up, Forgetting Sarah Marshall and TV series How I Met Your Mother, was responsible for getting the film into production.

"The Muppets were my first comic influence and I was in love with puppetry. We ended Forgetting Sarah Marshall with a lavish puppet musical and The Jim Henson Company designed the puppets," he says.

"Something started growing in my belly and we pitched it to Disney. It was a bit of a campaign by necessity. It's not easy to get a movie made, let alone a movie of this scope."

As well as co-writing the script with Forgetting Sarah Marshall director Nicholas Stoller, Segel – who makes and performs his own puppets – stars in the film as Gary, the brother of Walter, a new Muppet.

Gary, his girlfriend Mary (played by Adams) and Walter decide to leave their idyllic hometown of Smalltown, where people randomly burst out into song and dance, to meet Kermit and the original stars of the TV show in Los Angeles.

"Walter has that wide-eyed naivete the Muppets possess, and that's why he wants to be part of the Muppets," Segel explains.

Adams, who will next be seen as Lois Lane in Zack Snyder's Man Of Steel, admitted it wasn't difficult acting alongside Jim Henson's puppets.

"It's like every kids' dream – when you're playing with your stuffed animals, you wish they'd come to life and talk to you. That's what's so loveable about them – you just accept they are real."

The mother-of-one described the musical routines as "a lot of fun".

"I'm glad that I have jobs when I can sing and dance because I feel like I annoy my friends and family when I do it all the time at home anyways, so it's nice to have an excuse," she adds.

As well as Kermit, Miss Piggy, Segel and Adams, the latest big-screen adventure, directed by Flight Of The Conchords director James Bobin, features old favourites from the singing and dancing variety show including Animal, Fozzie Bear and Gonzo, alongside Chris Cooper as villainous oil baron Tex Richman.

"I wanted to sing and dance in a film! And, of course, to act with the Muppets," says Cooper.

The Muppets, who have pursued solo careers, have to reunite and put on a fundraising show to buy back the Muppets Studios from Tex, who plans to destroy it.

Notoriously picky Miss Piggy, who's resplendent in a plunging sparkly ballgown and white satin gloves, wasn't exactly ecstatic about making the movie.

"It was misery. I didn't care for a moment of it. I mean, I love my Kermie and I love spending time with him, but the rest of the Muppets, I could do without," she says.

Like the award-winning TV series, which ran from 1976 until 1981 and saw Elton John, Diana Ross, Debbie Harry and Roger Moore clamouring to cameo, the movie is packed with celebrities including Ken Jeong, Emily Blunt, Alan Arkin and many more.

"There are more cameos, but I can't talk about them," teases Kermit. "One of the ways the Muppets get big stars to be in our movies is by promising not to tell anyone about it – besides, it's more fun when you're watching the movie and are surprised by who shows up."

Segel admits it was easy getting the stars on board. "We didn't have to make any outgoing calls. There's an intrinsic love for the Muppets, so when people heard we were doing this movie, they showed up in droves to try to be in the film," he says. "We got some awesome cameos, and some weird ones too."

Taking charge of the music is Bobin's Flight Of The Conchords' colleague Bret McKenzie, who included musical classics The Muppet Show Theme, Rainbow Connection and of course Mahna Mahna, with his own original songs.

"I was looking for someone who would be best at musical comedy," says Bobin.

"Like me, Bret's a huge Muppets fan and during our Conchords break-times, we would watch Muppets videos on YouTube."

One of the songs McKenzie wrote, Man Or Muppet? (sung by Segel and Walter), has already won several critics' awards and is up for the prestigious Best Original Song at this year's Oscars, facing competition from Rio's Real In Rio.

"I'm not sure Bret can believe it. He has taken it in his stride; he's the most modest person I know," says Bobin.

Whether they triumph at the February 26 ceremony, one thing is for certain – the Muppets are set to reach new heights as they are introduced to a new generation.

"My daughter, who is four, hadn't heard of the Muppets when I started this and now she is in love with them. It's the best thing ever to introduce her to something I loved as a child," says Bobin.

Adams believes it is the Muppets' personalities which will ensure they appeal to generations to come.

"They're very honest, very identifiable. Jim Henson created something that was really special and unique, and I'm glad to see it alive after all of these years," she says.

Segel adds: "The Muppets remind us of who we wanted to be as kids. They have a sense of childlike wonder. Despite how cynical the world gets, they stay the same and they endure."

As Kermit says: "We're here to sing, dance, make people laugh and somehow make the world a better place. That may sound silly, coming from a frog, but the Muppets have always tried to inspire the world with silliness."

The Muppets is in cinemas on Friday, February 10.