The World Health Organization (WHO) has been receiving frequent reports about alleged chemical attacks in Iraq, especially from Mosul, the UN organization’s spokesman said Sunday.

“Events involving the possible deliberate use of toxic chemicals to cause harms to Iraqi men, women and children increased substantially in northern Iraq in 2016,” WHO spokesman Tarik Jasarevic said.

Since March of this year, the WHO has continued to receive “sporadic but frequent” similar reports, particularly from the northern city of Mosul, the spokesman said without assigning blame to ISIS terrorist group or any other conflict party.

While one chemical attack in Mosul was widely reported in early March, the German newspaper Welt am Sonntag reported Sunday that ISIS has allegedly used such weapons 71 times since 2014 in Iraq and Syria, according to the London think tank IHS Conflict Monitor.

In March, the International Committee of the Red Cross (ICRC) said that seven patients with symptoms consistent with an exposure to a toxic chemical agent had received treatment near Mosul.

Iraqi forces launched a perilous assault on the Old City on June 18, eight months into an offensive to retake Mosul, the country’s biggest military operation in years.

The part of Mosul that lies east of the Tigris river that divides the city was reconquered by January.