Naomi Campbell and her Russian billionaire boyfriend are rumoured to be on a ''break''.

The supermodel has been with Vladislav Doronin for around five years but it is believed their relationship has hit the rocks and they have decided to temporarily separate.

In the last few weeks, Vladimir has been spotted out with Naomi and was seen most recently at the Rose Bar at the Gramercy Park Hotel in the company of a beautiful blonde and the pair were last seen together on Miami Beach in in March.

In claims made to the New York Post newspaper, a source said: ''Naomi and Vlad have broken up, and he's been out partying in New York.''

Another source added: ''Naomi and Vlad have a complex relationship, and sometimes break up and make up ... They spend a lot of time apart due to work commitments.''

Naomi, 42, has had numerous work commitments over the past few months with her modelling competition show 'The Face' proving to be a huge hit in the US with a UK version now currently taping which kept her apart from the hotel and property mogul.

Despite their separation, the catwalk firecracker is expected to invite Vladimir, 50, to her 43rd birthday party on May 22 in Ibiza.