The very graphic video, which the news channel said was filmed covertly, showed severely wounded men blindfolded and chained to hospital beds. A rubber whip and an electrical cable sit on a table in one room.The situation is dire throughout the country, as Assad's forces continue attacking locations where opposition groups are known to be - including Deraa (where the protests first took hold).
"I have seen detainees being tortured by electrocution, whipping, beating with batons, and by breaking their legs," the employee told a French photojournalist who reportedly smuggled the video outside of Syria, according to Channel 4.
The authenticity of the film could not be independently verified.
The hospital employee said he tried to stop "the shameful things" that were happening but was called a traitor.
He said the torture was carried out by civilian and military surgeons and other medical staff including nurses. It reportedly took place in the ambulance section, the prison ward, the X-ray department and the intensive care unit. The footage was filmed over the past three months, Channel 4 said.
At least six people were killed on Tuesday, including a young girl, as Syrian forces launched a major assault on Herak, a town in the southern province of Daraa, a monitoring group said.Assad's forces also attacked a bridge that refugees were using to flee towards Lebanon.
The girl was shot dead by a sniper and five soldiers were killed in clashes with the rebel Free Syrian Army (FSA), the Syrian Observatory for Human Rights said.
"Large military forces, including tanks and armoured troop carriers, launched an assault on Herak," the Britain-based monitoring group added, citing residents.
And in Maaret al-Numan, a town in the northwestern province of Idlib, a 23-year-old man was shot dead by sniper fire, according to the Observatory. Security forces also killed two others in Idlib.
After fleeing the battered Baba Amr district in the flashpoint central city of Homs, the rebels regrouped in nearby Rastan, which the Observatory and activists said came under artillery fire on Sunday and Monday.
Rastan, bombed intermittently since February 5, is located on the motorway linking Damascus to northern Syria.
Qusayr, another town in Homs province that has fallen mainly under rebel control, was also targeted by heavy bombardment, according to Anas Abu Ali, an official with the FSA.