Rihanna and Katy Perry have attacked a former Big Brother contestant who launched a Twitter campaign promoting “managed anorexia”.

Kenneth Tong, who took part in the 2009 series of the reality show, claimed to be launching a size zero pill, but has since insisted he only said it to gain attention.

However, Tong's comments attracted criticism from a host of music stars, including Rihanna, who told women to ignore his messages.

"Girls are dying all over the world because of ignorant individuals like this,” she wrote.

Katy Perry re-tweeted Rihanna's post, before adding: “Preach!”

In a message today (January 12), Tong said: “The whole size zero thing is a hoax. It came about after an interesting discussion I had with a friend of mine.”

He apologised to anyone offended by the “scientific experiment” and said he planned to donate money to Beat, which helps people with eating disorders.

(by Jason Gregory)