West Midlands Police were alerted to a robbery which took place in Ley Hill Park in Northfield at around 11am on Wednesday 7 June.
A 43 a year old lady was when she was approached by three men who demanded that she gave them her jewellery whilst was walking her dog in the popular south west Birmingham park.
After refusing to do so, she was pulled to the ground and then struck to the head.
One of the men also slashed her arm with a bladed article, before making off with her jewellery.
A spokesperson for West Midlands Police said “Following enquiries of another incident in the same area, three men were arrested on suspicion of robbery and bilking offences, however they were later released without charge.”
The investigation is on-going and anyone with information is asked to call police on 101, quoting 20BW/118953J/17. Alternatively, contact Crimestoppers anonymously on 0800 555 111 or visit www.crimestoppers-uk.org