Radical Islamist preacher Abu Qatada, who was once reportedly described by security officials as Osama bin Laden’s right-hand man in Europe, has condemned the beheading of two American journalists by militants of the Islamic State, according to media reports published Monday.

Qatada, who is lodged in a prison in Jordan where he is being tried on terror charges, reportedly called the Islamic State, formerly known as ISIS, a “killing and demolition machine,” terming its fighters as the “dogs of hellfire.” The Sunni militant group recently executed James Foley and Steven Sotloff -- two American journalists -- in retaliation for U.S. airstrikes on the group's strongholds in northern Iraq.

“Journalists shouldn't be killed -- it's not permitted because they are messengers of the truth…The Prophet Muhammad said that the messengers should not be killed,” Qatada told reporters from the dock of a court in the Jordanian capital of Amman.

He also reiterated his earlier statements, reportedly made in July, in which he denounced the Caliphate established by the Islamic State in the captured territories of Syria and Iraq, calling it “void and meaningless.”

Abu Qatada, who was deported from the UK last year, is on trial in Jordan over an alleged terrorist plot aimed at the millennium celebrations in the country in the year 2000. Another case against the firebrand Salafist preacher, dealing with his involvement in a 1998 bombing plot, was dismissed by a panel of judges in June.

The verdict on the second case against him is expected to be announced on Sept. 24.

Qatada is considered to be extremely influential among the militants of Jabhat al-Nusra, which is the Syrian affiliate of al-Qaeda. As a result, his open condemnation of Islamic State is expected to further deepen the divide between the supporters of Islamic State and the al-Nusra front in Jordan.