Naomi Campbell's ex-boyfriend is reportedly dating her protege.

The 42-year-old model and 50-year-old Russian billionaire Vladislav Doronin recently ended their almost five-year-relationship and he has been spotted embracing Luo Zilin, a model Naomi mentored on her TV show 'The Face', on holiday in Spain.

A source told MailOnline: ''It's fair to say that Luo and Vlad met through Naomi, it's really unprofessional of Luo and it's not great behaviour on Vlad's behalf.''

Model Jocelyn Chew, who was also on 'Team Naomi' took to Twitter to voice her disapproval, saying: ''I'm completely shocked/disgusted W my 'teammate' Zilin. Never judge a book by it's cover. #truecolors love you @naomicampbell (sic).''

However, Luo, 25 - also known as Zi Lin - denied reports of a romance with Vladislav on Twitter, even though pictures have emerged of her kissing him.

She wrote: ''No, I'm not dating Vlad, No, I'm not his 'side chick', no, didn't f**k, No, I'm not an escort, nor have I ever been (sic).''

Meanwhile, Luo has also been fired from MIX Model Management in New York for ''ongoing unprofessional conduct''.

Neal Hamil, President, MIX Model Management NYC, said: ''Zi Lin's contract with MIX Model Management NYC was terminated last week due to ongoing unprofessional conduct and unacceptable work ethic.''