Erik Fosse, a Norwegian cardiologist, worked in Gaza hospitals during the recent war."It was as if they had stepped on a mine," he says of certain Palestinian patients he treated. "But there was no shrapnel in the wound. Some had lost their legs. It looked as though they had been sliced off. I have been to war zones for 30 years, but I have never seen such injuries before."

Dr. Fosse was describing the effects of a U.S. "focused lethality" weapon that minimizes explosive damage to structures while inflicting catastrophic wounds on its victims. But where did the Israelis get this weapon? And was their widespread use in the attack on Gaza a field test for a new generation of explosives?

The specific weapon is called a Dense Inert Metal Explosive (DIME). The weapon wraps high explosives with a tungsten alloy and other metals like cobalt, nickel, or iron in a carbon fiber/epoxy container. When the bomb explodes the container evaporates, and the tungsten turns into micro-shrapnel that is extremely lethal within a 13-foot radius.

Most of those who survive the initial blast quickly succumb to septicemia and organ collapse. "Initially, everything seems in order but it turns out on operation that dozens of miniature particles can be found in all their organs," says Dr. Jam Brommundt, a German doctor working in Kham Younis, a city in southern Gaza.

If by some miracle victims resist those conditions, they are almost certain to develop rhabdomyosarcoma (RMS), a particularly deadly cancer that deeply embeds itself into tissue and is almost impossible to treat. A 2005 U.S. Department of health study found that tungsten stimulated RMS cancers even in very low doses.

It appears DIME weapons may have been used in the 2006 Israeli invasion of Lebanon, but not enough to alarm medical workers. But in Gaza, the ordinance was widely used. Al-Shifta hospital alone has seen 100 to 150 victims of these attacks.

DIME is a U.S. invention. Did the Israelis get the weapons from the United States, or did they design similar ones themselves? Given the close relations between the two militaries, it isn't unlikely that the U.S. Air Force supplied the weapons or, at least, the specifications on how to construct them. And since the United States has yet to use the device in a war, it would certainly benefit from seeing how these new "focused lethality" weapons worked under battlefield conditions.

DIMEs weren't the only controversial weapons used in Gaza. The Israeli Defense Forces (IDF) also made generous use of white phosphorus, a chemical that burns with intense heat and inflicts terrible burns on victims.

Israel initially denied using the chemical. "The IDF acts only in accordance with what is permitted by international law and does not use white phosphorus," said Israel's Chief of Staff Gabi Ashkenazi on January 13.

But eyewitness accounts in Gaza and Israel soon forced the IDF to admit that they were, indeed, using the substance. On January 20, the IDF confessed to using phosphorus artillery shells as smokescreens, as well as 200 U.S.-made M825A1 phosphorus mortar shells on "Hamas fighters and rocket launching crews in northern Gaza."

Three of those shells hit the UN Works and Relief Agency compound on January 15, igniting a fire that destroyed hundreds of tons of humanitarian supplies. A phosphorus shell also hit Al-Quds hospital in Gaza City. The Israelis say there were Hamas fighters near the two targets, a charge that witnesses adamantly deny.

Eighteen-year-old Mona Al-Ashkar says she did not immediately know the first explosion at the United Nations (UN) school in Beit Lahiya had blown her left leg off. There was smoke, then chaos, then the pain and disbelief set in once she realised it was gone - completely severed by the weapon that hit her.

Mona is among the 5,500 injured that have international and Palestinian doctors baffled by the type of weaponry used in the Israeli operation. Mona's doctors at Gaza City's Al-Shifa hospital found no shrapnel in her leg, and it looked as though it had been "sliced right off with a knife."

Local doctors say a number of both widespread and unusual injuries may indicate that new types of weapons were used on the Gaza population during the war. Health officials are seeing wounds they have never seen before, or at least not on such a massive scale.

"There has been a significant loss of life here in Gaza for reasons that are unexplainable medically," said Dr. Skaik. Over 50 patients at Al-Shifa had two or more limbs severed, he says.

What is worrying health officials even more, however, is that some of the patients' organs are being ruptured with little or no sign of a shrapnel entry point.

"Normal shrapnel has a clear path, with both an entry and an exit point," said Dr. Mohamed Al-Ron, another surgeon at Al-Shifa hospital. "But someone's entire abdomen will be ripped open, and only after searching will we find a miniscule hole in the skin. Then we will find small black dots all over the organ, but we don't know what they are." It is an indication, he continued, that whatever is entering the body is exploding and doing the damage once it is inside. Multiple organs will fail, and will continue to fail even after surgery removes any shrapnel.

Some of the injuries, including multiple organ failure, mutilation and severed limbs, are so debilitating that Dr. Karim Hosni, an Egyptian doctor volunteering at the Al-Naser hospital in Khan Younis, says he wishes he could just end his patients' misery.

The International Atomic Energy Agency (IAEA), the UN's nuclear watchdog, said it would look into a claim made by the ambassadors of a number of Arab nations that Israel used depleted uranium in its recent attacks on Gaza.