A senior doctor has warned that police risk repeating a Hillsborough-type tragedy if they continue with tactics deployed during the recent tuition fee protests.

The anaesthetist from Aberdeen Royal Infirmary, who gave medical assistance to the protesters, said that officers forced demonstrators into such a tight "kettle" on Westminster Bridge that they were in danger of being seriously crushed or pushed into the freezing River Thames.

The 34-year-old doctor, who set up a field hospital in Parliament Square, said that people on the bridge suffered respiratory problems, chest pains and the symptoms of severe crushing.

"Police had us so closely packed, I couldn't move my feet or hands an inch. We were in that situation like that for hours. People in the middle were having real difficulty breathing.

"It was the most disturbing thing I've ever seen – it must have been what Hillsborough was like. The crush was just so great. Repeatedly I tried to speak to officers, telling them that I was a doctor and that this was a serious health and safety risk," said the doctor, who did not want to be named.

Her comments will raise fresh concerns over police tactics during the protest 10 days ago during which almost 50 police and protesters were hospitalised.

During the Hillsborough tragedy of April 1989, Britain's worst sporting disaster, 96 Liverpool fans died when police failed to control crowds and a lethal crush developed. Hundreds more were injured after being squeezed against the steel-fenced terraces of Sheffield Wednesday's stadium, which was hosting that year's FA Cup semi-final. The inquiry into the disaster led by Lord Chief Justice Taylor established that the main cause was a failure of police crowd control.

Student Danielle Smith, 21, from Dagenham, studying creative and professional writing at the University of East London, said she was squeezed so tightly during the kettle that the day after it felt "like I'd been in a car accident".

"I couldn't move, and it hurt to laugh, breathe, sleep, sit down and eat. To do anything just really hurt. For days after I took as many painkillers as I could a day. I had real trouble standing in such a tight space. Again people were getting crushed. I had a shield in my face a few times. The police just hit those closest to them, they weren't really thinking about who was in the wrong or right."

She said it was incredible that none of the hundreds of protesters sandwiched between two lines of riot police fell off the bridge: "The people around the edge, they were screaming, saying they thought they were going to fall off."

The Aberdeen doctor added: "The sides of the bridge were only waist high and all it would have taken is one stumble and someone could have gone over the side. I'm surprised that no one died there. And if anyone had been injured, I would have struggled to respond even if I was stood next to them." She said that when several police became caught inside the kettle they were screaming to get out. "They were experiencing what we were experiencing."

Her comments also include allegations of disproportionate police violence, pointing to the number of serious head injuries among protesters. Along with two colleagues who had volunteered to staff a field hospital, the doctor said they treated around 30 protesters.

"It got incredibly violent. The vast majority of injuries I saw were head injuries. I was surprised how much force the police had used. Between us we probably saw thirty folk. A couple of people also had injuries to their wrists and elbows where they had raised their hands to cover themselves from baton blows."

Witnesses say a section of the crowd were ushered from Parliament Square around 9pm onto Westminster Bridge before being kettled for around three hours until they were released.

A Scotland Yard spokesman said kettling was used to control sections of the crowd, who had became violent, while minimising force. He said that every effort was made to keep the crowd as safe as possible.