LONDON-- Glastonbury, one of the world's biggest music festivals, gets under way Wednesday facing angry criticism from some fans after rapper Kanye West was booked for the prime Saturday night headline slot.

Highlighting the five-day event's popularity, 150,000 tickets for costing £225 (315 euros, $360) each sold out in just 26 minutes when they went on sale in October before the line-up at Worthy Farm in Somerset, southwest England, was announced.

In total, 175,000 people will attend Glastonbury, which started in 1970 -- when admission was £1, including free milk from the farm -- and features hundreds of performances on dozens of stages from the mainstream to the downright bizarre.

But the presence of outspoken "Gold Digger" star West, who is married to reality TV star Kim Kardashian, has sparked controversy at an event known for its hippie roots.

Nearly 135,000 people have signed a petition to get him dropped.

The online petition against West -- who has sold over 100 million downloads and albums worldwide and won 21 Grammy Awards, but is often criticised for self-aggrandising comments -- says he should be kicked off the bill and replaced by "a rock band".

"Kanye West is an insult to music fans all over the world," the petition reads. "We spend hundreds of pounds to attend Glasto (the festival's nickname), and by doing so, expect a certain level of entertainment."

Emily Eavis, Glastonbury's co-organiser and daughter of founder Michael Eavis, said she had even received death threats over the booking, adding the abuse had been "just horrible".

"Kanye West is making the most exciting music at the moment," she said last month.

"He is an amazing force as a performer. For us, getting the biggest star in the world was an amazing coup."

West is not the first US hip-hop star to headline Glastonbury. In 2008, Jay-Z attracted similar objections but drew one of the festival's largest-ever crowds and won rave reviews for a set which riffed on the opposition he had faced from some fans.

Hawking to entertain kids

Preparations for the festival were hit last week by the withdrawal of Foo Fighters from the Friday night headline slot after frontman Dave Grohl broke his leg by falling off stage while performing in Gothenburg, Sweden.

Florence + The Machine were swiftly promoted up the bill to replace them.

Emily Eavis said: "There was only one person we wanted to call and that was Florence."

Other big names set to perform include The Who, Pharrell Williams, Motorhead, Mary J. Blige, Mark Ronson, Lionel Richie, Patti Smith, The Chemical Brothers, Alabama Shakes and Hozier.

For many people, Glastonbury is about more than just the music, with a wealth of areas on the 900-acre (four square kilometre) site devoted to everything from circus to cabaret and even a "free university".

"There will be enlightenments, awakenings, surreal happenings, Damascene epiphanies and people doing the strangest things in public," the organisers promise on the festival website.

Glastonbury has kept its traditional political activist tinge even as it has evolved into a major business over the years.

Russian punk protest band Pussy Riot will be holding a discussion event on one of the stages, while charities Greenpeace, Oxfam and WaterAid receive a donation from organisers and have volunteers on site.

The festival is also family friendly and many older fans bring their children to camp with them on site.

This year, youngsters will be treated to a special guest appearance by physicist and mathematician Professor Stephen Hawking in the Kidz Field area.

Glastonbury -- whose site is a working farm for the rest of the year -- often descends into a mudbath thanks to the heavy rainfall which can persist into the British summertime.

Festival goers this year will be relieved to note that conditions are forecast to be mostly dry.