Manchester City are to investigate chief executive Garry Cook after it was alleged that he sent an email to player Nedum Onouha’s cancer-suffering mother ridiculing her illness.

Cook denies sending the email, which is said to have been intended for director of football Brian Marwood, claiming that his account was hacked.

"Following allegations made to the football club by Dr Anthonia Onuoha, subsequently reported in today's media, the club can confirm that a board-led review has been launched into the matter," said a City statement released on Monday evening.

"When I opened up my emails and saw the message, it was the worst day of my life, even worse than being diagnosed with cancer," Dr Onuoha told The Sun.

"I couldn't understand how anyone could behave like that. I'm critically ill. I cried and cried for hours."

Owner Sheikh Mansour is aware of the allegation and Cook, or the person who sent the email, is thought to be unlikely to remain at the club.