WASHINGTON, Jan 17: Defence Secretary Donald Rumsfeld said on Wednesday US forces in Afghanistan had found more evidence that the Al Qaeda network was seeking chemical, biological and nuclear weapons, and the number of sites to inspect was growing.

The United States does not have evidence that Al Qaeda has acquired weapons of mass destruction but the materials indicate they wanted to use such deadly items, he said.

“In terms of having hard evidence of actual possession of weapons of mass destruction, I do not have that at this stage,” Rumsfeld said at a Pentagon media briefing.

Canisters found in Afghanistan initially appeared not to contain deadly chemicals, but would be brought back to the United States for further testing, a military spokesman said.

“We have not tested them completely yet. We are going to bring them back to the States and test them,” Army Col. Rick Thomas, a spokesman for Central Command which is running US military operations in Afghanistan, said.

“We don’t think there is anything in there, but until the tests are done, we just can’t say with certainty,” he said.

Two canisters unearthed about a week ago by a British engineering firm clearing mines near Kabul had the skull and crossbones symbol on them as well as warnings in Russian that referred to nuclear material, Thomas said.

Rumsfeld said earlier the canisters were believed to contain chemicals and that “externally they appear to be weapons of mass destruction”.

The number of suspected chemical, biological and nuclear weapon sites in Afghanistan is growing and US forces are now targeting more than 50, about 10 more than they have already inspected, Rumsfeld said.

“The number of facilities keeps going up,” he said.

“We have found a number of things that show an appetite for weapons of mass destruction — diagrams, materials, reports that things were asked for, things were discussed at meetings,” Rumsfeld said.

One site registered an elevated level of radioactivity but it appeared to be a result of depleted uranium on some warheads and not from any nuclear or radiological weapon of mass destruction, Rumsfeld said.

Depleted uranium is a heavy metal that can pierce armour and has small levels of radioactivity associated with it.

US forces found some missiles with depleted uranium warheads in the Kandahar area near the end of December, Thomas said. It was not known where al Qaeda obtained those weapons.

OSAMA HUNT: The US military pressed on with the hunt for Osama bin Laden and Taliban leader Mullah Mohammad Omar, getting help from Afghans and partner countries to locate them.