More than 150,000 people are expected to attend London's biggest free theatre festival, featuring stars from West End musicals, this weekend.

Actors including Laura Michelle Kelly, who plays Galadriel in the musical adaptation of The Lord Of The Rings, and Duncan James, who used to be in boy band Blue and now stars in Chicago, will perform on a giant outdoor stage at the event in Leicester Square. Called West End Live, the festival has been organised by Westminster council.

It will feature performances by the casts of Avenue Q, Dirty Dancing, Stomp, The Drowsy Chaperone, Mamma Mia!, The Sound Of Music, Fame, Little Shop Of Horrors and Menopause The Musical.

The London Gay Men's Chorus, Sylvia Young Theatre School and hip-hop dance troupe ZooNation will also take part.

There will be interactive workshops organised by tourist attractions including the Science Museum, the National Gallery and the Wallace Collection.

Robert Davis, Westminster's cabinet member for special events, said: "Anyone who comes to West End Live will not be disappointed.

"There is a fantastic line-up of free entertainment on offer, with everything from top West End shows to the latest in children's entertainment.

"We are thrilled to have so many top acts appearing. Their support and backing is proof of what a major attraction West End Live has become."

The Lord Mayor of Westminster, councillor Carolyn Keen, said she hoped the event, which clashes with the Glastonbury music festival, would attract people from across the country. "This is a unique opportunity to sample for free what London has to offer those who love West End shows, museums and galleries," she said.

"Whether you want to relax and enjoy the singing and dancing, or try your hand at cartoon drawing, Bollywood acting or stage make-up, there is something happening for all ages and interests. Leicester Square is the entertainment heart of our rich cultural city and many aspects of this cultural diversity will be on show this weekend."

Last year's festival attracted 130,000 people over the course of the weekend, with guest appearances from West End stars Bonnie Langford and Tom Conti. Visitors spent more than £2.2 million at shops, restaurants and other businesses in the area. The West End has the highest concentration of theatres of anywhere in the world. Theatreland attracts about 12 million visitors each year and contributes £1 billion to the economy.

West End Live takes place tomorrow and Sunday, from noon to 6.30pm each day. For more information and regular updates, visit the festival's website at www.westendlive.co.uk