Hamas security chief Tafiq Abu Naim was hospitalized on Friday after a car bombing, which Hamas called “a failed assassination attempt”, left him moderately wounded.

“General Tawfiq Abu Naim survived an assassination attempt Friday afternoon, after his car was blown up in the Nuseirat refugee camp in the middle of Gaza City,” Hamas Interior Ministry in Gaza Spokesman Iyad Bozm said in a statement following the explosion.

While Deputy Hamas Chief in Gaza later blamed Israel, announcing at a press conference that “we point our fingers directly at the occupation and its spies,” another Hamas statement described the attack only as “an act of cowardice that would only be perpetrated by the enemies of the Palestinian people and the homeland.”

According to the Times of Israel, reports indicate that Hamas officials in Gaza believe the Islamic State (ISIS) was behind the bombing. No group has yet claimed responsibility.

Abu Naim, who was released from the hospital on Saturday, indicated his belief that the attack was an attempt to derail the unity agreement between Hamas and the Fatah faction of the Palestinian Authority (PA), which will see the two Palestinian governments, ruling the Gaza Strip and the West Bank respectively, merging into a single body in the coming weeks.

“The objectives of those who committed this despicable act will not be achieved,” said Abu Naim. “We are determined to leave the split behind and realize the important national unity at all costs.”

The Hamas-Fatah unity agreement, brokered by Egypt, will restore PA control to the Gaza Strip seven years after it was seized by the terror group Hamas. The handover of the Strip and border crossings is set to take place by December 1.

Israel and the US have both expressed reservations about the impending unity, demanding that any reconciliation must be accompanied by a complete disarming of Hamas’s military wing. However, Hamas has said “no one” can force it to disarm.