Kanye West (L) and Jay-Z. (AFP file photo)

British rocker Bernard Butler has taken aim at rap heavyweights Jay-Z and Kanye West, branding them old men "who can't dance".

The former Suede guitarist was watching TV coverage of London's Hackney Weekend concert on Saturday but was left baffled when headliner Jay-Z called his pal West onstage to perform several songs with him.

And Butler was even more annoyed when he saw footage of the Big Pimpin' hitmaker's wife Beyonce dancing in front of the stage with her friends and aides, calling the Crazy in Love singer an "insincere PR trip".

In a series of tweets, the guitarist-turned-producer wrote, "I'm decades behind music and all popular culture. I see Beyonce as a nonstop insincere PR trip... How does anybody fall for that b**locks?... (She is) standing in the security pit surrounded by 100 sycophants."

He also criticised Jay-Z's performance, insisting it was poor compared to a previous appearance on BBC TV show Later... With Jools Holland, adding, "Jay-Z on 'Later' had an amazing drummer, live guitar player, and on the Radio 1 (Hackney Weekend) thing it was him and Kanye like a pair of 40 year old A&R (record company) men who can't dance shouting 'London oh yeah', whilst an iPod played Otis Redding. I can do that at home. But without them 2 falling around the front room."