Hamas, who lost senior leader Mahmoud al-Mabhouh in January after he was assassinated in an elaborate cloak-and-dagger operation in Dubai, has joined the government of the tiny emirate in saying it's convinced the likely perpetrators were members of the Mossad, Israel's intelligence and security agency.

Soon after Mr. Mabhouh was assassinated, the Islamist organization pointed the finger at its old adversary. But its complaints have grown louder in recent days, after Dubai released footage of the alleged 11-member assassination team, their photographs, and details on the European passports they traveled on -- all of them apparent forgeries.

On Wednesday, hundreds of Hamas militants rallied in memory of Mabhouh at the Jabaliya refugee camp in the Gaza Strip.

“The first question regarding Mabhouh is: who wanted to kill him? Second, who has the ability to assassinate him abroad?” says Hamas government spokesman, Taher Al Nounou. “All arrows point to Israel.”

Hamas says it will not yet reveal the evidence it claims it has that Israel is responsible for Mabhouh’s murder, instead saying it will allow Dubai authorities to complete their investigation before making any official announcements that could compromise their work.

Israeli Foreign Minister Avigdor Lieberman said on Wednesday there was no proof implicating the Mossad in the assassination and refused to confirm or deny their involvement..

Past assassinations

But the movement says Israel’s attempted assassination of Hamas political leader Khaled Meshaal in Amman, Jordan in 1997 and of its spiritual leader Sheikh Ahmed Yassin in Gaza in 2004 is proof Israel maintains an official policy of targeting its leaders – and is basing its strategy of retaliation on that assumption.

“Israel has assassinated our leaders and other Palestinian leaders in the past, and this is their policy,” says Mr. Al Nounou. “We have no official policy right now to take the fight abroad, but we know Israel has decided to take the fight abroad.”

Two reports emerged today, however, claiming Palestinians are also being held in both Dubai and Damascus on suspected involvement in the assassination. The UK’s Guardian newspaper reported Hamas operative Nahro Massoud is being questioned about the assassination in Damascus. The Israeli daily Haaretz reported that two Palestinians extradited from Jordan to Dubai last week – Ahmed Hasnin and Anwar Shekhaibar – are affiliated with Fatah, Hamas’ secular rival in the West Bank.

Hamas officials downplayed the reports of Palestinian involvement, saying they have no reason to believe the operation was planned by anyone but the Israelis, and that reconciliation efforts between Hamas and Fatah will continue.

The two parties have been bitter rivals since they fought a series of bloody street battles in 2007, leaving Hamas in control of Gaza and the Western-backed Fatah in power in the West Bank.

“These statements concerning PA involvement are too hasty,” says Ayman Taha, a senior Hamas official in Gaza. “This is not the official position of the movement, that the PA was involved. When the investigation is finished, we will announce who is behind the killing.”

Another senior Hamas official, Ahmed Yusuf, says while the loss of Mr. Mabhouh was significant for the movement, his death will not compromise the organization’s strength either in Gaza or abroad. Reports say Mr. Mabhouh was responsible for securing weapons for Hamas from Iran.