Three dozen mortar shells uncovered in Iraq earlier this month had no chemical agents, the Danish army says.
The shells had been buried for about 10 years
It is not clear why initial tests first showed they could contain blister gas, the Danish army said in a statement carried by the AP news agency.
The 36 shells were found in southern Iraq buried among building equipment, even though they appeared to have been abandoned for at least 10 years.
The US-UK coalition launched the war in Iraq over arms banned by the UN.
No weapons of mass destruction have been found since Saddam Hussein's regime fell, although US claims inspectors have found evidence of WMD-related programmes.
Field tests conducted by British and Danish inspectors indicated that the shells - found on 9 January - contained traces of blister gases - including mustard gas compounds.
But further tests by the Iraq Survey Group in South Iraq and the US Department of Energy's National Engineering and Environmental Laboratory in Idaho proved these results were incorrect.
"The results show the shells from the Danish area did not contain chemical warfare agents," the Danish Army Operational Command confirmed on Sunday.
Testing kits used on the shells would be sent to Denmark for analysis, the statement added.
Altogether 50 of the 120mm unmarked shells were recovered by Danish engineers in the desert area, north of Basra, which was a flashpoint in the Iran-Iraq War.
About 50 more shells are thought to still be buried in the area.
Local residents told troops they had recovered about 400 shells in recent years and had thrown them in the Tigris river, AP reported.