The top grossing Broadway musical of all time - The Lion King - celebrated its 20th anniversary in a big way on Sunday night.

British singer Elton John made a surprise appearance after a thunderous curtain call, performing for close to 1,700 invited guests - mainly the former cast and crew of the production, along with their families.

Accompanied by cast members, John played the piano as he sang Circle Of Life, an original song from the 1994 animated film's soundtrack, which is also part of the musical. He had collaborated with the musical's lyricist, Tim Rice, on three new songs for the onstage production, which premiered on Broadway in 1997.

This was one of many moments in Sunday night's special performance that got the audience in the Minskoff Theatre, in the heart of Times Square, on their feet.

Mr Victor Amerling, who was head of props for The Lion King for 10 years, was also on his feet to applaud the cast during the opening sequence, which introduces the imaginative use of puppetry in the show.

"It was a very nostalgic night, like a big reunion... When you do this for so long, it feels like family," said Mr Amerling, who is now head of the props department at Aladdin, another Broadway production.

The Lion King's composer, South African Lebo M, said of the 20th anniversary: "Excited is an understatement - I'm a little overwhelmed. Until a couple of days ago it was a bit surreal, now it's a bit like 20 years rolling back."

Since it opened in the Orpheum Theatre in Minnesota in 1997, 395 actors have been part of The Lion King, performing to more than 90 million people and helping the production earn more than US$7.9 billion (S$10.8 billion).

The musical, adapted from the popular Disney animated film, is based on the journey of a young lion cub, Simba, who is next in line to be king of the savannah after his father, Mufasa. His uncle, Scar, however, has ambitions to become king and manages to kill Mufasa before sending Simba into the wild. Simba eventually regains his crown with the help of his newfound friends.

As part of the show's 20th anniversary, a free show will be held on Broadway on Nov 15 and tickets will be given out via a lottery system.

Mr Thomas Schumacher, president and producer of Disney Theatrical Productions, said it is a chance to "thank New York City for 20 years of loving support".

The musical will make its way to Asia next year, with stops in the Philippines, South Korea, Taiwan and Singapore.

"While The Lion King has been to Singapore before, this is a different company... that I think will be really thrilling," said director Julie Taymor, referring to the international cast that will be performing here.

This is the second time it will be performed in Singapore. In 2011, 300,000 people watched the show over eight months.

The Singapore show, which will be performed at Mastercard Theatres at Marina Bay Sands, starts on June 27 and will run till Aug 5.

Tickets go on sale from Monday.