Amman: A leading Jordanian Islamist ideologist on Wednesday denounced the declaration of a “caliphate” by Islamist militants in Iraq and Syria, warning against more bloodshed.

“Can every Muslim and weak person find refuge in this caliphate? Or would it be like a sharp sword against all opponents?” Issam Barqawi, known as Abu Mohammad Al Makdessi, wrote on Facebook and on Islamist websites.

On Sunday, militants known as the Islamic State of Iraq and the Levant (Isil), declared a “caliphate”, an Islamic form of government last seen under the Ottoman Empire, straddling parts of Iraq and Syria.

The militants already control large swathes of territory in north and east Syria, and this month captured vast stretches of northern and western Iraq.

They ordered Muslims worldwide to pledge allegiance to their chief, Abu Bakr Al Baghdadi.

“What would the fate be of other Islamist fighters in Iraq, Syria and elsewhere?” asked Al Makdessi, who was freed on July 16 after serving a jail sentence for recruiting fighters for the Taliban.

Once mentor to Iraq’s now slain Al Qaida leader Abu Musab Al Zarqawi, before the two fell out over ideological differences, Al Makdessi warned against “Muslims who kill other Muslims”.

“Do not think you can silence the voice of justice by shouting, making threats, aggression and having no manners?” he asked.

“Reform yourselves, repent and stop killing Muslims and distorting religion.”

Experts say the declaration of the caliphate is a direct challenge to Al Qaida and could spark a contest for the leadership of the global extremist group.

They said it was unlikely that major groups linked to Al Qaida would immediately declare their allegiance to Isil.

Jordan’s Islamist movement is generally dominated by anti-Isil groups that support Al Qaida and its Syrian ally, Al Nusra Front.

The offensive in Iraq has also sparked fears in Amman that the Islamist militants will try to take their fight to the kingdom.

Jordan is already suffering from hosting more than 600,000 Syrian refugees, and has long faced the challenge of dealing with its own Islamist extremists, many of whom have joined Islamists or Al Qaida-linked groups in neighbouring Iraq and Syria.

On Monday, King Abdullah II appealed for international support to help Jordan deal with regional turmoil after the caliphate was declared.