Iraqi Prime Minister Haider Al-Abadi has defended Iran from having any responsibility over three Americans who disappeared from Baghdad last week.

At a meeting with Secretary of State John Kerry on Thursday, the Iraqi PM was asked if he thought the Iranians–who are close allies of Iraq–had been involved in any way.

“I don’t know about that. I doubt it very much. We don’t know if they have been kidnapped… They just went missing,” Al-Abadi responded.

But on Tuesday, Iraqi intelligence sources, along with U.S. officials, said the U.S. citizens were not “missing,” but instead were being held by an Iran-backed Shiite militia.

The Shiite militias have developed a strong rapport with Iraqi forces, often fighting side-by-side with them against the Islamic State.

On Friday, al-Abadi dismissed any possible political motive behind the suspected kidnapping.

“I don’t believe there’s any political thing out of this because what political gain would anybody get,” al-Abadi said from the World Economic Forum in Davos, Switzerland. “I think it’s mainly … criminal gangs, unfortunately, but we are going to find out.”

The Shiite militias have proven to be an important force in combatting Islamic State’s gains in Iraq. Yet, evidence has shown them utilizing the same barbaric tactics–such as beheading and torturing innocents–as the Sunni jihadi group.

And there are several Shiite militant groups in Iraq that are backed by Iran and view the United States as the enemy, making them potential culprits to the alleged kidnapping.

Iraq’s Popular Mobilization Committees, a Shiite militia group, fought against U.S. troops during America’s 2003 invasion that saw the toppling of Saddam Hussein’s regime.

Another militia, the Saraya al-Salam, engaged in battle against U.S. forces from 2003 to 2011, according to reports.

A separate Shiite militia, Asaib Ahl al-Haq, which is backed by Iran, has frequently spoken out against the United States, ABC News reports.

On Friday, the U.S. Embassy in Baghdad said that Iraqi and American officials are working together to locate the missing Americans. Officials told Fox News that the Americans were kidnapped from a “suspicious apartment,” but did not elaborate further.

No group or person has publicly claimed responsibility for the kidnapping of the American citizens.

The suspected kidnapping occurred just days after the U.S. and Iran negotiated a prisoner exchange, with Iran claiming the U.S. paid a $1.7 billion dollar ransom for the freedom of four Americans. The U.S. State Department claims the payment was “separate but simultaneous,” and not a ransom.