 -- New videos surfaced online this week that allegedly show U.S.-supported Iraqi security forces severely beating and executing prisoners by throwing them off a cliff after liberating Mosul from ISIS, which according to investigators at Human Rights Watch offer credible evidence of human rights abuses.

Images of war crimes allegedly carried out by Iraqi units trained, equipped and advised by American forces deployed there have routinely been posted on Facebook, Instagram and Twitter for years but identifying victims and confirming the time and place of such atrocities is often difficult.

Human Rights Watch says it was able to confirm the location of one of four incidents in videos posted on Iraqi Facebook pages in recent days, which the group says showed regular Iraqi army troops and Federal Police beating several ISIS suspects with rifle butts, a table and their fists, as well as a video showing two detainees tossed off a cliff and being shot after landing on the ground below.

"These horrific reports of mistreatment and murder have been met by silence from Baghdad, only further fostering the feeling of impunity among armed forces in Mosul,” said Belkis Wille, an investigator for HRW. “Prime Minister al-Abadi should immediately launch investigations into these serious crimes that appear to have been exposed in these videos, and also look into other recent reports of violations by armed forces in the context of the Mosul battle.”

Wille said all four videos were published on Facebook this week by an Iraqi, Salah al-Imara, who regularly publishes information about military activities in and around Mosul.

The new images are reminiscent of those broadcast during an ABC News investigation that aired on “Nightline” in May called “The Torture Tapes," in which award-winning Iraqi photojournalist Ali Arkady embedded with an Iraqi special forces unit and was allowed to film hours of torture sessions conducted by officers from the unit.

The ABC investigation with Arkady and his agency VII Photo found that the Iraqi Emergency Response Division was advised by U.S. troops and the unit also used American-donated heavy weapons such as "Carl Gustaf" anti-tank launchers and Humvee trucks, even though they had been banned under U.S. law from receiving military assistance because of past human rights abuses.

The past abuses by the Emergency Response Division, such as beheadings of prisoners, were disclosed in an earlier ABC News investigation in 2015, "Dirty Brigades: No Clean Hands in Iraq's ISIS Fight."

In each ABC investigation, as with other allegations that Iraqi government troops were committing war crimes by torturing and executing civilians and ISIS suspects, Baghdad has suggested the images were "ISIS fabrications" or promised investigations which seem to have produced few publicly disclosed results.

The Emergency Response Division and Federal Police are both elite paramilitary units within Iraq's Ministry of Interior, known for its close ties to Iran's security services and to Shi'a Muslim militias. Both were banned from receiving aid under the Leahy Law, which requires foreign military units be vetted for human rights abuses before receiving arms or training, in March 2015, the day after ABC's first investigation,” Dirty Brigades” aired on "World News Tonight.” In May, however, a spokesperson for the U.S. military command in Baghdad, Army Col. Joe Scrocca, told ABC News that the Federal Police had been reinstated.

"Some of the Federal Police divisions previously prevented from receiving equipment and training have since overcome past issues and are now permitted to be trained and equipped, but the ERD have not," Scrocca said.

In response to ABC News’ most recent investigation, “The Torture Tapes,” focusing on the Emergency Response Division, it appears some of the officers in ERD were relieved from field duty, but ABC News has not learned of any further actions.

On Thursday, two Iraqi military spokespersons appeared at a Pentagon briefing and addressed the latest allegations.

Iraqi Brig. Gen. Yahya Rasoul Rasoul said they are following the social media reports that have surfaced, and anyone found guilty of violating human rights "will be held accountable," while suggesting the new videos could be fabricated by those seeking to diminish the victory over Mosul.

The Interior Ministry has created an investigative committee to look into these allegations, and some members of the force who have engaged in inappropriate conduct have already been suspended, Brig. Gen. Saad Maan, another spokesperson for Baghdad Operations Command and the Iraqi Ministry of Interior, told reporters, adding that the Iraqi government "wants to be transparent" as it looks into these reports.

But Human Rights Watch says even the Iraqi Army soldiers shown tossing two men off a cliff in one of the new videos are part of the large force trained by the U.S. and its allies since 2015, and they are seen on video carrying American-made and donated M16A2 rifles.

"These are the very troops that the US has been arming and training for years," Wille, the HRW investigator, told ABC News today. "While primary responsibility for investigating these abuses lie with the Iraqi authorities, I hope the coalition and the U.S. in particular are taking a hard look at these abuses and asking themselves why we still see soldiers carrying out war crimes with impunity."