Iraq's military authorities have confirmed elite forces have detained 14 militia members who remain in custody amid an ongoing investigation.
Friday's statement by the Iraqi Joint Operations Command came hours after sources said the Counter Terrorism Service (CTS) had raided a base in southern Baghdad of Kataib Hezbollah (KH), an Iran-backed group which the United States has accused of targeting bases hosting US troops and other diplomatic interests in Iraq.
The statement said a special investigation committee was formed by the interior ministry following the arrest of the 14 individuals.
In an apparent dismissal of earlier claims that the detainees had been released, the joint command also said "the defendants have been handed over to the security services until the investigation is completed and a decision is made by the judiciary".
A high-level security source, who wished to remain anonymous, also told Al Jazeera "an investigation was still under way" and that "no one has been released from among the detainees".
According to the statement, an arrest warrant was issued after Iraqi authorities received intelligence about a potential attack on the Green Zone, a heavily fortified area in central Baghdad housing government buildings and foreign missions.
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The raid was aimed at pre-empting an imminent attack and also resulted in the seizure of several rockets and two launching pads that had allegedly been previously used in attacks against military and diplomatic interests, according to the statement.
Dozens of rocket attacks in recent months have targeted US interests in Iraq, including the US embassy in the Green Zone and military bases hosting US soldiers. Six have taken place just during the past two weeks.
Although the joint command did not name which group the detainees belonged to, sources told Al Jazeera they were members of KH, one of the groups under the umbrella of the Popular Mobilisation Forces (PMF) or Hashd al-Shaabi.
Another security source said the operation had targeted KH as well as members of recently-formed militias including Ashab Ahl al-Kahf, Usbat al-Tha'ireen and Jund Soleimani. In a strongly-worded statement early on Friday, Jund Soleimani called on "the mujahideen" to continue their resistance and achieve victory.
A third security source told Al Jazeera that one of the detainees was a foreigner, possibly an Iranian national, and that the CTS held the group responsible for targeting the Green Zone and Baghdad airport with Katyusha rockets.
A source from the PMF leadership denied the claims to Al Jazeera, saying that a CTS raid of a PMF base in southern Baghdad was based on "false" information about the presence of "terrorists".
The US has accused Kataib Hezbollah of targeting military bases hosting US troops in Iraq [File: Thaier al-Sudani/Reuters]Negotiations for release
While the exact location of the detainees remains unclear, Hisham al-Hashimi, an Iraqi analyst who has sources close to the Iraqi government, told Al Jazeera the "defendants were transferred from a prison belonging to the CTS to a detention centre under control of al-Hashd in northeast Baghdad".
He also said that negotiations led by PMF leaders and members of the powerful Iran-backed Fateh coalition were continuing but had so far failed to secure the defendants' release.
Earlier on Friday, reports had circulated that Fateh leader Hadi al-Ameri had intervened on behalf of the detainees to negotiate their release.
Later in the day, former Iraqi prime minister and leader of the Iran-backed State of the Law Coalition, Nouri al-Maliki, issued a statement on Twitter condemning the "assault" on the PMF members while calling for self-restraint and respect and preservation of the PMF and the CTS alike. He also offered to mediate.
Initial statements by several PMF leaders, including by KH spokesman Mohamed Mohie, had said the detainees were released shortly after their detention on Thursday.
"Detained members of the Hashd have been released ... [and] returned to their bases. The incident was quickly resolved," he told Al Jazeera on Friday morning.
Commenting on these statements, Talha Abdulrazzaq, a research fellow at the University of Exeter's Strategy and Security Institute, said the PMF's statements appeared to have been a "face-saving measure" after presumed KH members late on Thursday flooded the streets in and around the Green Zone in pick-up trucks to demand the release of the detainees.
Videos widely circulated on social media showed these individuals, some of whom appeared to be armed, eventually retreating. Initial reports suggested that a group had laid siege to a CTS building inside the Green Zone, but these were later denied.
Threatning the Iraqi PM directly in the heart of Baghdad by members and loyalists of Kataib Hizbullah, He is referring to Alhmedawi whl was designated on the terror list and is being tasked to replace Abu Mahdi Al Muhandis. pic.twitter.com/7iKNzpyg8A— Steven Nabil (@thestevennabil) June 26, 2020
While estimating that the 14 will likely be released soon, Abdulrazzaq told Al Jazeera their detention was a message from new Prime Minister Mustafa al-Kadhimi to the militia groups and the US.
"The move showed that al-Kadhimi was trying to assert control, but with US backing. He is beholden to these powers in Parliament and to the good favour of the US and Iran, without whom he would never have been in power in the first place," Abdulrazzaq said.
"Al-Kadhimi has since promised to curb these different factions," he explained, adding that the move was also an attempt by the recently elected prime minister to "show the US that he wants to play ball ... [and] will want to see something in return".
An Iraqi delegation, including al-Kadhimi, is scheduled to travel to Washington, DC next month to resume high-level talks with the US leadership
In the first round of talks, launched on June 11, both sides agreed in a joint statement to reduce the number of US troops in Iraq over the coming months.Tensions high
Meanwhile, tensions remained high in Baghdad on Friday, with leaders of pro-Iran armed groups condemning the events of the previous night while others called for de-escalation.
In a statement on Twitter, Nasr al-Shimmari, deputy secretary-general of the pro-Iran Harakat al-Nujabaa group, warned that targeting the PMF would come at a huge cost to the country's internal stability.
"We warn against any attempt to pull [opposing] sides towards an internal conflict during these difficult times. Such attempts will definitely fail."
In a statement shared on Telegram, KH leader Abu Ali al-Askari said the raid and arrests were an attempt by "this monster al-Kadhimi" to hide his involvement in the "criminal murder of two martyrs and their comrades".
His words were in reference to Iranian General Qassem Soleimani and Hashd deputy leader Abu Mahdi al-Muhandis who were killed in a US drone attack at Baghdad airport on January 3.
The incident saw escalating tensions between Washington and Tehran almost spill into a full-blown regional conflict.