Security guards at a charity run have been accused of barring a runner suffering from hypothermia and exposure from going through barriers to reach medical treatment.

The men are said to have refused to let a car carrying Chris Arnold, 38, from Portslade, through to see St John Ambulance staff for around 30 minutes.

Driver Gary Herbert, 51, from Surrey, picked Mr Arnold up in his car when he saw him in trouble by the roadside at the Sussex Beacon Half Marathon in Brighton on Sunday. The day was cold and it was raining heavily. He said: "He could barely walk and he was absolutely ashen. He could have been having a minor heart attack for all I knew.

"I think it's disgusting. They were the most ridiculous jobsworths I have ever seen."

Mr Herbert, a builder, his wife Sheila and their two-year-old granddaughter Grace were on a day trip to Brighton and stopped to act as Good Samaritans when they saw Mr Arnold in trouble at a water stand.

Mr Herbert said: "Someone flagged us down and asked us to get Chris some medical attention. He was in a terrible state."

They helped Mr Arnold, a store manager for Superdrug and an experienced runner, into the car and drove to the slip-road at the east end of Madeira Drive.

Stewards there said they would be too close to the start and finish line and asked them to drive round to the other entrance by the Palace Pier.

When they arrived two Select Security employees told Mr Herbert he could not come through and placed a barrier in front of the car.

Mr Herbert explained that he had a sick runner who needed medical attention.

He said: "One of the men said: I don't care if he's dying, mate, you're not coming through here.' They were acting like a couple of nightclub bouncers."

Mr Herbert tried to see if Mr Arnold could walk to the medical tent but he was disoriented and unable to use his legs.

Mr Arnold said: "I am astounded that I was prevented from getting treatment."

Mr Herbert said he and some other runners tried to persuade the men to let Mr Herbert through or radio St John Ambulance for help, but they refused to use their radios.

In the end they contacted Mr Arnold's girlfriend on Madeira Drive via her mobile phone and she spoke to the crew who sent an ambulance round. Finally the guards let the ambulance through to lead Mr Herbert's car along Madeira Drive.

Steve Curry, the race director, said: "The possibility of any breach that puts the safety of a runner at risk is taken very seriously and we will be further investigating this incident."

Mr Arnold said: "I must thank Mr Herbert and the St John Ambulance staff who were wonderful."