A man has been arrested on suspicion of attempted murder after a 31-year-old Italian national was stabbed in the head in a “vicious” mugging in a busy park.

The victim is believed to have been attacked in the head with a screwdriver in Dulwich Park, south London, just after 1pm on Thursday.

He had been sitting in the park when a man approached him and demanded his phone before allegedly stabbing him.

Detectives investigating the incident arrested a 26-year-old man on Sunday on suspicion of attempted murder, robbery and non payment of fines.

The victim was rushed to hospital after sustaining life-threatening injuries in the attack. His condition remains critical.

A friend, who was with the victim in the park at the time, told the Standard: “It was a vicious and shocking attack… now my friend is in intensive care and we are praying he will be ok.”

“Me and my friend were just sitting on the lawn with our dogs who were playing by us,” she said. “I noticed a guy on his bike crossing the grass.

“He returned within a few seconds, got off his bike and raised a sharp objected and said to my friend ‘give me your phone’.

“My friend just said ‘what?’ then he stabbed him in the head. There was no time for him to even get out his phone and give it to him.

“The guy shouted at me ‘you don’t move’ and I raised my handbag towards him as if to say ‘just take my bag’.

“Then the guy stabbed my friend again, this time in the left side, took my bag and rode off.”

She described how she used her scarf to stem blood coming from her friend’s head, before emergency services arrived.

An air ambulance landed near a packed children’s playground less than 100 yards away and the man was rushed to King’s College Hospital.

Parents said top private schools in the area including Alleyn’s and Dulwich College sent a message warning them not to allow their children to go to the park because of the incident.

Gerry Fletcher, who was in the park with a friend, said: “It’s just horrific. It’s such a lovely, peaceful park and the playground would have packed with children. We just hope the man is going to be ok.”

A parks worker told the Standard: “We were told by police to look out for any screwdrivers that might be in bins. Police are checking all the bins this morning. It’s a shocking thing to have happened.”

Detective Superintendent Helen Lyons, from Southwark police said: "I would like to thank those in the community for coming forward with information as this has greatly assisted the investigation.

“Whilst we have made an arrest this evening I would urge those that have yet to come forward and speak to us to do so as the information you hold may be vital to progressing this investigation further."

Any witnesses or anyone with any information is asked to call police on 101 or contact via Twitter @MetCC. To give information anonymously contact Crimestoppers on 0800 555 111 or contact online at crimestoppers-uk.org.