A York man has admitted killing a 87-year-old woman when he burgled her home on New Year's Day.

Peter Anthony John Harris, 33, "knocked Elsie Mowbray flying" as he tried to make his escape, Leeds Crown Court heard. She hit her head and fell to the floor. She died at York Hospital eight days later.

Harris, of no fixed address, pleaded guilty to the manslaughter of Mrs Mowbray, burgling her home in Victoria Court off Leeman Road, York, and robbing two people of cash and a wallet in a separate incident in Turpin Court, York, also on New Year's Day.

Mr Justice Lindblom said he needed to know more about the danger Harris could pose to other people before sentencing him and adjourned the case until July 8.

Leeds Crown Court heard part of a police statement by Mrs Mowbray's son Richard Mowbray, the only eyewitness to events in her home on New Year's Day. In it, he described how he arrived with a newspaper after Harris had forced his way inside. He saw Harris on the stairs and his mother in the sitting room.

The court heard Harris had been searching the house looking for items to steal. Mr Mowbray said he put his hand up and told Harris to stay where he was while he rang the police.

His mother was standing by a table behind him, watching them. As he turned to get a phone, Harris pushed past him, calling him different names, and went past Mrs Mowbray.

"He knocked her flying and her head hit the floor. The man (Harris) pushed past my mum and caused her to fall," the statement said.

Nicholas Barker, representing Harris, told Leeds Crown Court he accepted that Mr Mowbray's account was correct and that the burglar had been intoxicated at the time. He did not say whether Harris had taken drugs or been drinking.

Harris was impassive when he entered his pleas. He had previously denied the charges of manslaughter and robbery. The burglary charge was added to the indictment earlier in the hearing.

The judge told him he needed to know as much as possible about his offending leading up to his latest offences and his background before sentencing him.

Harris had previous convictions for violence including causing actual bodily harm to a prison officer when he was in hospital, serving a prison sentence in 2012.

"There is, on the face of it, a clear escalation in the gravity of his offending," the judge said. He ordered the probation service to prepare a report on Harris, who had hoped to be sentenced immediately.

Harris was remanded in custody until he is sentenced. He has been in prison since he was arrested on January 2.

The maximum sentence for both manslaughter and robbery is life imprisonment.