A 15-year-old girl was swimming in the sea off Southbourne Beach at around 4pm on Monday 4 September when she was struck by a rock, which is believed to have been thrown toward her.

As a result of the incident, she sustained a fracture to her skull and facial fractures.

Police Constable Hele Leech-Wilkinson, of Bournemouth CID, said: “This incident left the young victim with nasty injuries and was understandably a very distressing experience for her.

“We have been conducting enquiries into this matter and have now spoken further with the victim and obtained additional details. I understand there were a number of other people in the vicinity at the relevant time and I am now in a position to appeal for witnesses to the incident, or anyone who may have captured relevant mobile phone footage, to please contact us.”

Anyone with information is asked to contact Dorset Police at www.dorset.police.uk or by calling 101, quoting occurrence number 55230141969. Alternatively, independent charity Crimestoppers can be contacted anonymously online at Crimestoppers-uk.org or by calling Freephone 0800 555 111.