The Iraqi army has been paying salaries to at least 50,000 soldiers who don’t exist, Iraqi Prime Minister Haider al-Abadi said Sunday, an indication of the level of corruption that permeates an institution that the United States has spent billions equipping and arming.

A preliminary investigation into “ghost soldiers” — whose salaries are being drawn but who are not in military service — revealed the tens of thousands of false names on Defense Ministry rolls, Abadi told parliament Sunday. Follow-up investigations are expected to uncover “more and more,” he added.

Abadi, who took power in September, is under pressure to stamp out the graft that flourished in the armed forces under his predecessor, Nouri al-Maliki. Widespread corruption has been blamed for contributing to the collapse of four of the army’s 14 divisions in June in the face of an offensive by Islamic State extremists.

With entry-level soldiers in Iraq drawing salaries of about $600 a month, the practice of “ghost soldiers” is likely to be costing Iraq at least $380 million a year — though officials say that’s probably only a fraction of the true expense.

The corrupt practice is often perpetrated by officers who pretend to have more soldiers on their books in order to pocket their salaries, experts say.

Abadi’s announcement was met with applause in parliament. He said that the perpetrators would be tracked down eventually but that his priority is to end the practice as soon as possible.

“The problems are wide, and it’s an extremely difficult task which is going to involve some strong will,” said Iraqi security analyst Saeed al-Jayashi. “Training is weak and unprofessional.”

The United States is focusing its efforts on three divisions in order to begin effective counteroffensive operations against the Islamic State, which controls around a third of the country’s territory.