A British photographer wounded in Homs said the bombardment of the besieged Syrian city amounted to a "medieval siege and slaughter," and he denounced the Damascus government as "murderers".
Paul Conroy, 47, was speaking from a hospital bed in Britain, where he returned a couple of days ago after being smuggled into Lebanon on Tuesday.
"In Baba Amr there is nowhere to run. It's a slaughterhouse in there," he told CNN in a telephone interview, describing how people would be gunned down by snipers if they left their homes to venture into the streets in Homs.
"There are actually no military targets within Baba Amr. All of the intense shelling is in fact directed at the civilian population," he said.
"It would be wrong to call this a war. This is a medieval siege and slaughter. I would hesitate to use the word war."
Conroy was working for Britain's Sunday Times when he was caught in an attack in the Baba Amr district of Homs on February 22. The assault killed his US reporter colleague Marie Colvin and French photographer Remi Ochlik.
Conroy said the Syrian government's promise of an investigation into the deaths of the two journalists was "laughable," and that those guilty of killing them should go on trial at The Hague for crimes against humanity.
"I was with Marie when she was killed and I know who killed her," he said.
"Professional artillery men targeted, bracketed and murdered Marie Colvin. They murdered Remi. This was murder, there's no need for investigation.
"The Syrian regime -- I mean I -- you know, I'm sitting there mourning the loss of a friend and a colleague and I have to listen to this nonsense from the murderers themselves. It's like the murderers are investigating the murderers," he added.
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Conroy said in an earlier interview with Britain's Sky News that "it's a massacre, an indiscriminate massacre of men, women and children."
The former soldier said Syrian government forces had begun their attacks at 6:30 every morning, "systematically moving through neighbourhoods with munitions that are used for battlefields".
He said the humanitarian situation when he was there was "more than a catastrophe", as there was no power or water, and food was scarce.
"There's still thousands of people in Homs... they're living in bombed-out wrecks, children six to a bed, rooms full of people waiting to die.
"They see no relief, nothing, other than waiting for the moment the soldiers come in, or the shell comes through the door," he said.
Baba Amr became a symbol of the months-long uprising against President Bashar al-Assad's regime and was under siege for nearly four weeks until rebel fighters staged what they called a tactical retreat on Thursday.
Conroy said that since the international media had pulled out of Homs, the communications lines between the rebels had gone down.
"I fear for what is happening. There's no restraint with cameras there -- God knows what's going to happen now the cameras have gone," he added.
Conroy said he was feeling "remarkably well, all things considered". He had two large wounds in his leg and doctors pulled a three-inch (7.6 centimetre) piece of shrapnel out of his back that he did not even know was there.
He paid tribute to Colvin, "a unique person", noting: "To work with her was an absolute privilege. She was tenacious, one of the bravest people I know.
"Marie died doing something she was completely passionate about. She was in one of the most dangerous situations in the world at this current time, and she just wanted to tell the truth. She was horrified."
The International Committee of the Red Cross said Colvin's body, along with that of Ochlik, was being taken from Homs to Damascus on Friday, although it was unclear what will happen to it from there.
A spokeswoman for Britain's Foreign Office, while recognising Colvin's US citizenship, said: "We have been in touch with the Sunday Times and they are making arrangements for repatriation with the relevant authorities."