Hamas chief Khaled Meshaal and top Islamist leaders in Jordan on Friday attended the burial of a senior member of the Palestinian movement who was killed this week in Damascus.
Around 500 people took part in the funeral of Kamal Hussein Ghannaja, whose coffin was taken from a mosque in Amman's east to a nearby cemetery, where he was buried amid tight security.
"Allahu akbar, Allahu akbar (God is greatest). Hamas, you are the gun and we are the bullets. Martyrs are beloved of God," they chanted.
Hamas has said Ghannaja, a Jordanian, was killed on Wednesday in a Damascus suburb, accusing Israel's spy agency of having carried out an attack.
"All options are open. Investigations are still under way," Khalil Hayyeh, a senior Hamas leader, told AFP at the funeral.
"There were burn marks on his body. So maybe he was targeted or it was the result of an accident at home."
Ghannaja was a deputy of Mahmud al-Mabhuh, a senior Hamas military commander found dead in a Dubai hotel room in 2010. Investigators in the Gulf emirate have accused Mossad of that murder.
Syria has long allowed Hamas to operate offices in Damascus, but the Palestinian group has in recent months quietly moved most operations elsewhere as an uprising rocks the country.
Meshaal, who is in Jordan on his second official visit this year to improve ties with Amman, met on Thursday with King Abdullah II and top officials, including Jordan's intelligence chief.
Relations between Hamas and Jordan have been strained since 1999 when the authorities expelled Meshaal and three other Hamas members after the group was accused of threatening the kingdom's security and stability.