The United States is looking into reports that ISIL terrorists used chlorine gas against Iraqi security forces, U.S. Secretary of State John Kerry said on Friday.

The United States is looking into reports that ISIL terrorists used chlorine gas against Iraqi security forces, U.S. Secretary of State John Kerry said on Friday.

Kerry, speaking to reporters after meeting his South Korean counterpart, said he was unable to confirm media reports that chlorine gas was used against Iraqi police officers last month.

"These allegations are extremely serious and we are seeking additional information in order to be able to determine whether or not we can confirm it," Kerry said.

The Washington Post reported on Friday that 11 Iraqi police officers were rushed to a hospital north of Baghdad last month with symptoms that are consistent with chlorine poisoning.

The newspaper said Iraqi forces have reported two other crude chlorine gas attacks in Iraq since ISIL terrorists took over large areas of the country.

"The use of any chemical weapons ... is against international law and these recent allegations underscore the importance of the work we are currently engaged in," Kerry said.

"Obviously it can affect tactical decisions within that strategy, but our fundamental strategy remains absolutely clear," he added.