The sources on Saturday said that Zeidan arrived last week in the Syrian town of Raqqa to join IS ranks.
Known as an influential speaker and youth leader within the hard-line Jordanian Jihadi-Salafist movement in the northern city of Irbid, the cleric is a vocal supporter of IS.
Zeidan recently posted fatwas and speeches on the Internet attacking Salafist leaders Abu Mohammad Al Maqdissi and Abu Qatada for their criticisms of IS.
IS members confirmed Zeidan’s arrival to the so-called “caliphate”, or territory under the jihadist group’s control in Iraq and Syria, in messages posted via the social networking site Twitter on Friday.
It was unclear how Zeidan got there, with sources within the Jordanian Salafist movement claiming that he illegally crossed into Syria from Jordan last Tuesday.
Meanwhile, Hneity, the number two leader of the Jordanian Salafist movement, confirmed via Twitter and Facebook on Friday that he has joined IS in Syria and arrived on “caliphate soil”.
His mediation was ultimately rejected by both sides, and he has since believed to have been acting as an adviser to IS. Despite remaining active on social networking sites, Friday’s posts marked the first time Hneity publicly declared his allegiance to the group.
Zeidan and Hneity’s arrival raises to 20 the total number of Jordanian clerics believed to be serving in leadership posts within IS.