Thousands participated in Fukha's funeral, among them Hamas senior official Ismail Haniyeh and Hamas leader Yahya Sinwar.
Fukha was released from prison in 2011 as part of the Gilad Shalit prisoner exchange deal and was deported to the Gaza Strip.
In the past, Fukha denied leaks by Israel's security forces saying that he—along with other released prisoners—had founded Hamas's West Bank headquarters and had helped organize and conduct terror attacks against Israelis from the Gaza Strip.
"The reports leaked by the Israeli Shin Bet using the Zionist newspapers have only one purpose—to give the Shin Bet an excuse to harm released prisoners in the future, whether they are in the West Bank, in Gaza Strip or even abroad," claimed Fukha, adding that "it seems odd that a security organization leaks things that are supposed to be secret."
Fukha denied the allegations made following the leaks, saying that "they carry no truth."
Hamas' Deputy Director Khalil al-Hayya warned that "if the enemy believes that the assassination will cause a power shift, he should know that the Izz ad-Din al-Qassam Brigade (Hamas's military wing) know to react similarly."
The leader of the Islamic Jihad movement in Gaza, Mohamed Al-Hindi, said that "the occupation hoped to crush the resistance through the murder of the martyr Fukha."
Hezbollah also denounced his assassination, saying that the fingerprints of "the traitorous Zionist enemy" are clearly visible on it, responding that "this crime is another proof of the traitorous spirit lying within the abusive enemy and emphasizes the duty to keep fighting the abusive enemy until its banishment from all occupied territories."
Fukha's father, who still lives in Tubas in the northern West Bank, also accused Israel of the assassination, saying, "Israeli intelligence officers came to our house many times and gave us messages that Mazen would be liquidated if he continued with his actions."
The family watched the funeral on television in their home in Tubas.
(Translated & edited by Lior Mor)