Ban agreed to take on the subject after the two spoke on the phone on Thursday night, Foreign Ministry sources told news agency dpa.
Eyewitnesses have reported that gas was used against the inhabitants of Kobane on the Syrian-Turkish border, which has been under siege by the Islamic extremists for weeks.
Many people in the city are suffering from breathing problems and other symptoms of poison gas.
The Washington Post reported that 11 Iraqi policemen involved in a battle with Isis fighters in September were also brought to hospital in the capital Baghdad with similar symptoms and were diagnosed with chlorine gas poisoning.
And the New York Times reported that left-overs from former dictator Saddam Hussein's chemical weapons programme could have fallen into Isis' hands when it captured the Muthanna chemical weapon plant northwest of Baghdad.
Iraqi government officials claimed in June that all weapons stored at the plant were destroyed.
On Thursday Steinmeier confirmed to journalists that the government was considering sending more troops to train the Kurds as part of an EU mission.
A fact-finding team has also been sent to northern Iraq to examine the conditions for a training deployment by European armies.
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