Manchester City chief executive Garry Cook has been accused of sending an insensitive email to the mother of City defender Nedum Onuoha, apparently mocking her battle with cancer.

According to The Sun, Dr Anthonia Onuoha received the message from Cook’s account, but it appears that the mail was intended for City's football administrator Brian Marwood.

Cook, however, has denied sending the email and believes that someone hacked his account to send the message.

"When I opened up my e-mails 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 anybody could behave like that. I'm critically ill."

Cook has promised an internal inquiry at the club, and the incident has been referred to the FA and Premier League by Dr Onuoha.