A prominent jihadi preacher lashed out Friday against Islamic State militants for burning to death a Jordanian pilot, saying the action was, "not acceptable in any religion."

Abu Mohammed al-Maqdesi, considered a spiritual mentor for many al Qaeda militants, spoke a day after being released from more than three months in detention in Jordan.

His release and harsh criticism of the Islamic State group come at a time when the Jordanian government is trying to win broad popular backing for intensified airstrikes against the militants in response to the killing of the pilot.

In Amman, several thousand people -- including Jordan's Queen Rania -- marched in support of King Abdullah II after Muslim noon prayers. The crowd unfurled a large Jordanian flag and held up banners in support of the king's pledge of a tough military response to the killing of the pilot, Lt. Muath al-Kaseasbeh.

"We all stand united with the Hashemite leadership in facing terrorism," one banner read.

Earlier this week, Islamic State militants released a video showing the pilot being burned to death in a cage. The gruesome images have sparked widespread anger in Jordan and the region.

Jordan joined a U.S.-led military coalition against the militants in September, but said it would intensify air strikes in response to the killing of the pilot. On Thursday, dozens of fighter jets struck IS weapons depots and training sites, Jordan's military said.

In an interview with the Jordanian TV station Roya, al-Maqdesi said that the burning of the pilot "is not acceptable by any religion and by anyone."

The cleric indicated that he had been involved in back-channel talks to arrange a possible prisoner swap to win the release of the pilot, who was captured after his plane crashed over Syria in December.

Jordan offered last week to swap an al Qaeda prisoner for the pilot, but said after the release of the video that it became clear that the pilot had already been killed in early January.

Al-Maqdesi said he believed the militants were never serious about arranging a swap.

"During my communication, they lied and they were evasive," he said. "They acted like they were interested (in a swap), but in fact they were not interested."

He also criticized IS for declaring a caliphate last year in the areas under its control in Syria and Iraq. Al-Maqdesi said a caliphate, or state run according to Islamic law, is meant to bring Muslims together, but that the militants have been a divisive force.

A decade ago, al-Maqdesi was considered a mentor of the al Qaeda branch in Iraq, a precursor to the Islamic State group. However, the cleric fell out with his proteges over their methods, including attacks on fellow Muslims.

Jordan arrested the cleric in October, after he criticized Jordan's participation in a military strikes against Islamic State. Jordan, which borders Syria and Iraq, joined the coalition in September.