The Palestinian movement Hamas denied that its leadership had decided to strike Israeli interests abroad, vowing to avenge the killing of top militant in a time and place of its own choosing.
"There is no change until this moment in (Hamas's) policies in carrying out the fight and confronting the Zionist aggression on our people," said a statement from the movement's information office received by AFP in Beirut.
Hamas "reserves the complete and legitimate right to respond to this cowardly crime at a suitable time and place, and in the way that best serves the higher interests of the Palestinian people."
Earlier, Hamas politburo member Mohamad Nazzal told AFP in Beirut that "until today, the issue of carrying the fight outside Palestine is under study and no decision has been taken in that direction."
Hamas founding member Ezzeddin Sobhi Sheikh Khalil was killed in a car bomb blast in Damascus on Sunday that was blamed on Israel's Mossad spy agency.
"Following the assassination operation, the Hamas leadership is studying the consequences of this incident, but we cannot say that there is a change in the general policy of keeping the fight inside Palestine," Nazzal said.
Nazzal said he could not confirm the authenticity of a statement published in Gaza in which the Ezzedin al-Qassam Brigades, the armed wing of Hamas, vowed to take the battle "outside Palestine."
"We hold Mossad directly responsible for this very dangerous development that moved the fight outside Palestine and which attacked the sovereignty and stability of a country," he said.
Israeli officials and the army said they had no information about the strike, although a source close to Prime Minister Ariel Sharon said: "It is obvious that Damascus is little more than a sanctuary for terrorists."
The United States has also accused Damascus of backing groups it considers terrorist and earlier this year imposed sanctions of Syria.
Israel has frequently threatened to strike Hamas militants abroad, including in Damascus, where Hamas politburo chief Khaled Meshaal has been based since a failed Mossad attempt on his life in Amman in 1997.
Meshaal, who emerged as overall Hamas leader after Israel assassinated two other top figures earlier this year, is thought to top the Jewish state's most-wanted list.