Helen Cole, 48, was pronounced dead at Styal prison in Wilmslow, Cheshire, after staff attempted resuscitation and paramedics were called, the Prison Service said.

She was remanded into custody on Friday, accused of stabbing her 19-year-old son Andrew to death.

Andrew Cole's body had been found at the home he shared with his mother in Thornton, near Fleetwood in Lancashire, shortly after 2am on Wednesday.

Officers went to the Coles' house in Belvedere Road after receiving a call from Mrs Cole saying her son was seriously hurt. A post-mortem examination revealed he died from a stab wound.

His mother, a domestic help, was charged with his murder on Thursday and appeared at Wyre Magistrates' Court on Friday.

In court she spoke only to confirm her personal details and her solicitor indicated that she would plead not guilty to the charge of murder. It was expected that Mrs Cole would plead a defence of provocation and ask for the charge to be reduced to manslaughter.

Miss Wendy Lloyd, prosecuting, told Wyre magistrates that the defendant called police and said her son had been seriously hurt and was collapsed in bed at their home in Belvedere Road. In her initail police statement she said she thought he had been hurt in a fight.

Miss Lloyd said that the defendant changed her story considerably in her second police interview and admitted she had had a fight with her son when he came home which had culminated in her stabbing him. She said their relationship had been bad for a while.

A Prison Service spokesperson said: "Our sympathies are with the family of Mrs Cole at this time. As with all deaths in custody, the Prisons and Probation Ombudsman will conduct an investigation."