Kennedy said organisers tried to "dictate" his "musical decisions"
Maverick violinist Nigel Kennedy says he has been "prevented from performing" at the Classical Brit awards.
The 51-year-old wanted to play with glamorous string quartet Bond, but says the Brits committee vetoed his choice.
Organisers confirmed that "artistic differences" with Kennedy had "proved insurmountable", while the star's manager said he was "dumbfounded".
Andrew Lloyd-Webber is due to receive an outstanding achievement award at the ceremony in London on Thursday.
It is the 60-year-old's first Brit award - and comes more than 20 years after his Requiem Mass won a Grammy for best contemporary classical composition.
On hearing of the honour last month, the Phantom Of The Opera composer said: "I am absolutely thrilled that my music is being recognised, and delighted to be receiving the award."
Tenor Alfie Boe has two nominations for this year's awards, including male artist and album of the year.
In the best male category he will compete against Mexican lyric tenor Rolando Villazon and conductor Sir Colin Davis, who won the award in 2002.
Classical pianist Angela Hewitt, cellist Natalie Clein and operatic soprano Anna Netrebko will battle it out in the female artist of the year.
Musician and TV presenter Myleene Klass is hosting the ceremony at the Royal Albert Hall.
Organisers say that Kennedy's departure from the show has not left them short of performers.
They highlighted an appearance by heart-throb virtuoso David Garrett, who is said to be an heir to Kennedy's throne.
Other artists appearing at the ceremony include Bryn Terfel, Andrea Bocelli and Sarah Brightman.
All of the musicians will be accompanied by the London Chamber Orchestra - which is thought to be the source of Kennedy's disagreement with the Brits committee.
The Brighton-born violinist said he originally planned to perform Mozart or Beethoven but was told by organisers that his performance must last around the same length as a pop song.
Bond have sold more than four million records
When he suggested playing jazz instead, he said the idea was also rejected.
He eventually settled on a gypsy violin piece Czardas, by Vittorio Monti, but after two days of rehearsals with Bond, he was told they had not been approved as performers by the organisers.
Kennedy claims rival record companies on the Brits committee had made the decision because they were "threatened by me" which could "only be taken as a compliment".
"I was looking forward to this because it had become clear that this was going to be one of my best performances, not just musically but as a visual TV spectacle as well," he said.
Dickon Stainer and Thomas Kaurich, co-chairmen of the awards, said: "It is regrettable that Nigel Kennedy will no longer be performing.
"Nigel is a great artist with a unique vision, but artistic differences have proved insurmountable."