It was a shocking attack on a man the police described as 'vulnerable and defenceless' – a 60-year-old homeless man.

Yesterday, homeless people joined in the condemnation of the attack on one of their own, known to them as Old Man Billy.

The man was set upon while sat in a sleeping bag beneath the Novi Sad Friendship Bridge in the early hours of Wednesday.

He had to be taken to the Norfolk and Norwich University Hospital with head injuries after the attack, which Norfolk police said was totally unprovoked.

It happened on the south side of the bridge, which connects King Street to Riverside, at about 1.30am and police are appealing for help in tracking down the attackers of the man, who was released from hospital late last night.

'Buff', 34, who has been homeless for around 15 years, described Billy as a solitary and harmless man who had lived in Norwich for only two months.

He said: 'That's just wrong that it happened to someone like him. Billy's quiet, he wouldn't hurt a fly. He was very well liked. Everyone respected him, looked after him.'

He said he believed Billy was married and had two daughters, but had found himself on the streets after he turned to drink when his wife became ill.

The attack has already been condemned by charities which work with the homeless, and YMCA chief executive Tim Sweeting said: 'Just because people do not have a house does not mean they should not be valued and treated as human beings.'

He added that, because homeless people are often reluctant to report attacks to the police, he believed they were, sadly, far more common than statistics suggested.

Derek Player, general manager at St Martin's Housing Trust, which runs the Bishopbridge House hostel in William Kett Close, said the charity had previously tried to help the man.

He said: 'We are aware of the incident and have been concerned for his safety for some time. We are always full at Bishopbridge House, but when vacancies become available we try to offer places to those most in need.

'There are always one or two, who, for whatever reason, do not want to come into the hostel and this man falls into that category.

'We try to engage with everybody, but it is not always reciprocated. We have been concerned about him as he was obviously defenceless and very vulnerable.'

It is far from the first time that homeless people have been attacked in Norwich.

Last Christmas Eve, a 28-year-old Good Samaritan stepped in to stop two men who were assaulting a homeless man close to the Job Centre Plus in Pottergate and was himself assaulted. In 2007 officers launched an appeal after a vicious attack on a homeless man in Norwich's Prince of Wales Road was uploaded to video sharing site YouTube.

And in 2002, Big Issue seller Keith Swan, 32, was repeatedly punched and kicked by at the corner of Brazengate and Queen's Road in Norwich. He died from head injuries two days after the attack and two men were later jailed after admitting manslaughter.

Anyone who has information about the attack at the Friendship Bridge should call PC Keith Oldmeadow on 0845 456 4567 or Crimestoppers on 0800 555 111.

Do you have a crime story for the Evening News? Call crime correspondent Ben Kendall on 01603 772423 or email ben.kendall@archant.co.uk