A 77-year-old woman was taken to hospital after being punched in the face by a man who forced his way into her home.
The intruder left the house in Richmond Road, Aylestone, empty-handed after demanding money but not before he struck the pensioner in the face.
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Police said the attack happened at about 3.30pm on Wednesday.
The investigating officer Detective Constable Matthew Wiggins is appealing for information.
He said: "This was a nasty attack on an elderly woman in the middle of the day at a busy period and there would have been people around.
"There is also a possibility this man could have approached other properties nearby before targeting this house so he could have been seen in the area some time before 3.30pm.
"If you may have seen the suspect either before or after the offence, or have any information that may assist, please contact me."
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The suspect is described as white, of skinny build and was wearing a blue hooded top.
He is believed to have made off on foot possibly towards Aylestone Road.
Anyone with any information is asked to contact DC 2063 Wiggins on 101.