Some 60 militants from the Islamic State terrorist group were killed in clashes with peshmerga forces in Iraq's northern city of Mosul, a Peshmerga commander told Anadolu Agency on Tuesday.
The group, made up of all men, were accused of being spies who had placed themselves within the ISIS community on behalf of the Iraqi government.
Witnesses claim the "spies" had been bound together and dropped into the basin as sick ISIS members watched their bodies dissolve.
The barbaric execution of the 25 Iraqis was carried out in the ISIS stronghold of Mosul, in the north of the country.
The Islamic State executed 25 prisoners by lowering them into a massive Value-Added Tax of highly corrosive nitric acid, according to Iraqi news reports.
"ISIS put the citizens in a large tub containing nitric acid inside one of its headquarters".
It is normally used in manufacturing ammonium nitrate for fertilizer and explosives, organic synthesis, photoengraving, etching steel, and reprocessing spent nuclear fuel.
The terrorist group has continued losing control over territory across Iraq and Syria, a U.S. Military spokesman said this week, including nearly half of what it had once held in Iraq.
Those tallies had gone up in recent weeks, Pentagon spokesman Peter Cook said.
The US Defence department said: "The number right now in Iraq is about 45% of the territory they once held has been recovered".
Iraq has been dogged by rampant insecurity since 2014 when IS overran Mosul and declared a self-styled "caliphate" in parts of Iraq and Syria.
An estimated 40% of land once controlled by ISIS has been lost.