The Danish army said on Saturday that their initial tests have yet to be confirmed. 36 120mm mortar rounds were found a day earlier, but the army suspects they have been buried for at least 10 years.
"All the instruments showed indications of the same type of chemical compound, namely blister gas," the Danish Army Operational Command said on its website.
"However, this will not be confirmed until the final tests are available," it said in a statement after the initial examination of liquid leaking from the weapons.
Results of final tests are likely to be ready in about two days.
Blister gas, an illegal weapon which ousted Iraqi leader Saddam Hussein said he had destroyed, was extensively used against the Iranians during the 1980-1988 Iran-Iraq war.
Although it can kill if it enters the lungs, it is used mainly to weaken infantry by making the skin break out in excruciatingly painful blisters.
Danish army officials added that 100 more rounds could be buried at the site.
There are several hundred Danish soldiers working with a British-led multinational force responsible for security in southern Iraq.
In Baghdad, the US military said the mortar rounds had been found buried 75 km south of Amara, north of Basra.
"Most were wrapped in plastic bags, and some were leaking," Brigadier General Mark Kimmitt told a news conference, adding that it was likely the weapons were left over from the Iran-Iraq war.
Still no WMDs
The US administration had cited the threat of illicit weapons of mass destruction as a principle reason for launching war on Iraq in March last year. But no such weapons were found.
The United States earlier this month pulled out from Iraq a 400-member military team specialising in the disposal of weapons of mass destruction, in what the New York Times said was "a sign that administration might have lowered its sights" and viewed it as less likely that such weapons would be found.
But the White House played down the move, saying that the group focused on hunting weapons was remaining in Iraq.