Khloe is not a Kardashian - Robert Kardashian allegedly expressed doubts over her paternity

More drama erupted for Kim Kardashian and her family, as the ex-wife of her late father today claimed Kim's sister Khloe was not his daughter. 

Two of Robert Kardashian's ex-wives have come forward saying he confided in them that he was unsure of the paternity of the now-27-year-old.

Jan Ashley, who married the businessman after Khloe's mother Kris Jenner, said: 'Khloe is not his kid -- he told me that after we got married.'

And Ellen Pierson, 63, who married Robert in 2003 just two months before his death, has also come forward after eight years of silence to 'tell the truth' about the Kardashian family.

The reality star has hit back at the claims, calling them 'really low'.

In an explosive interview with Star magazine, Ashley said: 'He just kind of looked at me and said [it] like it was a matter of fact. He said "Well, you know that Khloe's not really a Kardashian, don't you?"

'And I said… "OK" and that was it.'

She claims Khloe, who is married to Dallas Mavericks basketballer Lamar Odom, knew she had a different father to her sisters and younger brother Rob.

'Khloe brought it up all the time. She looked nothing like the rest. She was tall, had a different shape, light hair, curly hair. Didn't look anything like the other three children.'

She said Robert, who is of Armenian descent, had told her that he and Kris were not sleeping together at the time Khloe was conceived.

'[But] he never would have considered a DNA test. He loved her very much. Robert did question the fact that Khloe was his,' Ellen said.

'Any normal man would if they knew their wife had cheated on him.'

Khloe has responded to the claims today on Twitter.

She wrote: 'The audacity you have to mention my father’s name like this! Should be ashamed of urself! I let a lot of things slide but this one is really low… YOU ARE DISGUSTING! (yes you know who YOU are).'

Kris, 56, recently admitted in her new book that she cheated on Robert during their marriage.