The revelations emerged at this year's annual security conference in Munich where world leaders gathered to discuss international security policy.
Abadi said during his address in Munich that there were groups operating outside the state's control within the Popular Mobilisation. He also appealed for international assistance in reining them in.
There have been reports of Iraqi Prime Minister Abadi dissolving the mainly Popular Mobilisation amid differences between the premier and the volunteer forces.
The reports followed a deadlock between Abadi and Iran-backed Popular Mobilisation leaders who were said that they were not complying with his orders, according to Al-Arabiya.
The reports say Abadi wants to include the Popular Mobilisation in the Iraqi army especially after his failure to include more Sunni fighters to the units.
|The allegations have come as a surprise to Iraqi officials who held al-Abadi responsible.|
"As the leader of al-Hashd al-Shaabi, Prime Minister Haider al-Abadi's serious confessions confirm our suspicions of infiltrators and criminals within the group," said Mohammed al-Karbuli, member of the Iraqi parliamentary security committee.
"His sudden awakening to the matter and plea to the international community to eliminate the rogues is rather suspicious," he added.
However, "the confession does not relieve al-Abadi of his legal and constitutional responsibility in exposing the names and identities of those lurking within factions of al-Hashd that have committed crimes in Tikrit and Muqdadiyah," said al-Karbuli.
The Iraqi official called on the prime minister to abandon his "double standards" while requesting the international community take on his confession as the "leader of the al-Hashd al-Shaabi group."
Legal expert, Abdulsalam Mohammed told The New Arab that the PM's confessions "pose a serious allegation to the group that must be dealt with legally."
"The PM will be held accountable if he does not offer an official judicial complaint with solid evidence," he added.
The Popular Mobilisation group, al-Hashd al-Shaabi in Arabic, is a state sponsored organisation consisting of over 40 Iraqi militias. The force was created in response to a fatwa by the religious cleric, Ayatollah Ali al-Sistani who called for armed opposition to the Islamic State group in 2014 as it took control of large parts of Iraq.