A Jordanian convicted in connection with the 2002 murder of a US diplomat in the kingdom was among six Al-Qaeda-linked militants that King Abdullah on Wednesday ordered freed.
"The king has instructed the government to take the necessary legal measures to free the six convicts," the palace said, naming the men without giving details.
Salafists, who espouse an austere form of Sunni Islam, have repeatedly held streets demonstrations to demand the release of their relatives.
The palace did not elaborate on its reasons for freeing the prisoners.
One of them is Mohammad Issa Dumos, who was sentenced for 15 years in prison for his role in the assassination of USAID official Laurence Foley, shot at close range outside his Amman home.
The remaining five are in jail for plotting to attack former intelligence officers in Jordan, planning jihad against foreign troops in Iraq and Afghanistan and funding terror activities.
"We welcome the king's instruction," Salafist leader Mohammed Shalabi, known as Abu Sayyaf, told AFP.
"Fifty members of the Salafist movement are detained in Jordan. The government has promised us to free all of them."