AMMAN — A Jordanian jihadist ideologist and Al-Qaeda cleric on Wednesday denounced the declaration of a "caliphate" by Sunni 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 Mohammed Al-Maqdessi, wrote on Facebook and on jihadist websites. On Sunday, militants previously 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, who renaming themselves the Islamic State (IS), already control large swathes of territory in north and east Syria, and this month captured vast stretches of northern and western Iraq. "What would the fate be of other Islamist fighters in Iraq, Syria and elsewhere?" asked Maqdessi, 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-Qaeda leader Abu Musab Al-Zarqawi, before the two fell out over ideological differences, Maqdessi 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 said. Experts say the declaration of the caliphate is a direct challenge to Al-Qaeda and could spark a contest for the leadership of the global group. Jordan's jihadist movement is generally dominated by anti-IS groups that support Al-Qaeda and its Syrian ally, Al-Nusra Front. The offensive in Iraq has also sparked fears in Amman that the Sunni militants will try to take their fight to the kingdom. On Monday, King Abdullah appealed for international support to help Jordan deal with regional turmoil after the caliphate was declared. Rebel groups in Syria seek aid Rebel groups from northern and eastern Syria on Wednesday demanded aid from the country's exiled opposition to allow them to fight against the Islamic State. "We, the leaders of the brigades and battalions... give the National Coalition, the (opposition) interim government, the (rebel) Supreme Military Council and all the leading bodies of the Syrian revolution a week to send reinforcements and complete aid," the statement said. "Should our call not be heard, we will lay down our weapons and pull out our fighters," it added. "Our popular revolution (against Syrian President Bashar Al-Assad)... is today under threat because of the (Islamic State), especially after it announced a caliphate," said the statement. IS first appeared in Syria's war in late spring 2013. It has since taken control of Raqa in northern Syria, much of Deir Ezzor in the east, and parts of Aleppo province. — Agencies