At least 32 people have been killed and 50 injured in a suspected chlorine bomb in Iraq's Diyala province, police say.
The attack happened in an open-air market in the village of Abu Sayda at about 2000 (1600 GMT) on Tuesday.
A police spokesman in the provincial capital Baquba said doctors at a local hospital believed the nature of victims' burns suggested poison gas.
Use of chlorine bombs has become more common since the start of the year, says a BBC correspondent in Baghdad.
Last month a bomb using chlorine and high explosive killed 35 people in Ramadi, west of the capital.
Chlorine - widely used as a cleaner and purifier in areas of poor water sanitation - is easy to obtain in Iraq.
Chlorine gas burns the skin on contact and can be fatal after a few breaths.
In February the United States military reported finding a bomb factory near Falluja, where chlorine car bombs were being constructed.
Diyala province - with its mixed Shia and Sunni Muslim population - has been the scene of frequent violence of a sectarian nature as well as attacks by anti-US insurgents.