Abu Sabah knew he had witnessed something unusual. Sitting in November last year in a refugee camp in the grounds of Baghdad University, set up for the families who fled or were driven from Fallujah, this resident of the city's Jolan district told me how he had witnessed some of the battle's heaviest fighting.

"They used these weird bombs that put up smoke like a mushroom cloud," he said. He had seen "pieces of these bombs explode into large fires that continued to burn on the skin even after people dumped water on the burns".

As an unembedded journalist, I spent hours talking to residents forced out of the city. A doctor from Fallujah working in Saqlawiyah, on the outskirts of Fallujah, described treating victims during the siege "who had their skin melted".

He asked to be referred to simply as Dr Ahmed because of fears of reprisals for speaking out. "The people and bodies I have seen were definitely hit by fire weapons and had no other shrapnel wounds," he said.

Burhan Fasa'a, a freelance cameraman working for the Lebanese Broadcasting Corporation (LBC), witnessed the first eight days of the fighting. "I saw cluster bombs everywhere and so many bodies that were burnt, dead with no bullets in them," he said. "So they definitely used fire weapons, especially in Jolan district."

Mr Fasa'a said that while he sold a few of his clips to Reuters, LBC would not show tapes he submitted to them. He had smuggled some tapes out of the city before his gear was taken from him by US soldiers.

Some saw what they thought were attempts by the military to conceal the use of incendiary shells. "The Americans were dropping some of the bodies into the Euphrates near Fallujah," said one ousted resident, Abdul Razaq Ismail.

Dr Ahmed, who worked in Fallujah until December 2004, said: "In the centre of the Jolan quarter they were removing entire homes which have been bombed, meanwhile most of the homes that were bombed are left as they were."

He said he saw bulldozers push soil into piles and load it on to trucks to carry away. In certain areas where the military used "special munitions" he said 200 sq m of soil was being removed from each blast site.

The author is an unembedded journalist reporting from Fallujah