Jordanian Information Minister Marwan Muashar said in Amman that the accused man, identified as Ziad Qishawi, was not in Jordan and that the state registrar had no record of him.
Earlier this week, Palestinian police announced that they had uncovered a plot by Hamas fundamentalists to assassinate Arafat when he made a scheduled visit to a Gaza Strip cemetery April 28.
Col. Tawfiq Jaber, who heads Palestinian intelligence in Gaza, said two parcels of explosives and two mines had been prepared for the attack.
Palestinian secret service officials said the militants had been hiding in a central Gaza neighborhood.
Jaber presented six of seven Hamas members who had been arrested in connection with the plot. One of the men, identified only as Motaz, said he was asked three months ago by Qishawi to carry out the assassination.
The group said they had turned themselves in to Palestinian officials after rejecting the assassination plot.
In Amman, Hamas spokesman Ibrahim Ghosheh denied any knowledge of the alleged plotter.