More than 100 protesters staged a desperate demonstration outside Croydon University Hospital last night over the treatment of a critically ill father-of-two.

Police guarded the hospital's entrance as an emotional crowd, many of them family and friends and some carrying banners and placards, repeated chants calling for "justice" for 22-year-old Marcus Campbell.

Mr Campbell, of Thornton Heath, is in a coma at the hospital after suffering a rare brain stem inflammation and his family have been told he will not be resuscitated if his heartstops. 

His mother Sandra and sisters are also furious that some family members have been banned from visiting him following an altercation at the hospital. 

Nearly 15,000 people have signed a petition, launched by Mr Campbell's sister Siobhan Chin on Tuesday, condemning "inhumane, disgraceful, unjust and all in all bad practice".

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More than 100 people attended the protest

Tonika Campbell, 21, another of Mr Campbell's sisters, accused the hospital of planning "legal euthanasia".  She said: "We feel that Croydon University Hospital are playing God with my brother's life, by determining his length of time left to live or not." 

Mr Campbell, who has two daughters aged three and six, first reported to the hospital on July 7 complaining of nausea, breathing difficulties and blurry vision.

Doctors gave him antibiotics for a suspected viral infection, but his condition worsened and he was taken by paramedics to St George's Hospital, where he was diagnosed with a brain inflammation and fell critically ill. 

He was transferred to Croydon University Hospital, where he remains in intensive care, last week.

Tonika said her family had been told doctors would not treat Mr Campbell as he had little chance of survival.

She said: "Put simply they told us that they would not resuscitate my brother if his heart was to stop beating and that if he got an infection they would not treat him as, 'He is dying and we do not want to prolong his death'."

She added: "They are giving up on him. It is not their choice to make. We are his family. He has two young children.

"The worst thing is doctors at St George's asked him if he wanted to be resuscitated if he went into a coma and he nodded his head. If he was prepared to make that sacrifice, we cannot give up on him."

Tonika and Siobhan, 29, were both barred from seeing their brother after police were called following a row at the hospital about his treatment. 

Their mother, Sandra Palmer, 48, last night collapsed to the floor in anguish as police officers and security guards prevented her entering the hospital with her daughters.

Croydon Health Services NHS Trust, which runs the hospital, defended the ban today and said it had "an overriding duty to protect our patients and staff".

But Tonika said: "We are a strong family and a lot of my mum's strength is from myself and my sister. Her son is lying in there and for us not to be able to go in there is breaking her. She had a panic attack."

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Police guarded the hospital to prevent protestors entering

At last night's heated but non-violent protest, which lasted around three hours, the crowd chanted "Mayday murderers" in reference to the hospital's former name and called a hospital representative to speak to the family. 

Following the protest, a trust spokesman said: "This is a heart-breaking time for the family and we want to do more to support them. We have arranged for an urgent second opinion of Marcus' care, which will take place later this week. 

"This external review will be led by an independent clinical expert who is completely separate from us. Their findings will be shared with the family.

"Our doctors and nurses are continuing to provide around-the-clock care to Marcus and are taking all reasonable steps to make him as comfortable as possible."

He added: "Marcus' children and mother can of course be with him on the intensive care ward, but we have asked the family to limit visitors to two at a time.

"There are currently visiting restrictions in place, and the reasons for this have been discussed with the family and are being reviewed on a daily basis. 

"We have an overriding duty to protect our patients and staff, and we will take any decisions that are necessary in the interests of safety for our patients and staff on the intensive care unit."

The hospital declined to comment on details of Mr Campbell's care.

Mr Campbell's family, who said this morning they had not been informed of the review of his care, are planning to stage a second protest at the hospital at 6pm today.

Family members including Ms Palmer are also to approach Labour leader Ed Miliband for help when he visits Croydon this afternoon.