Hamas forces have killed 32 members of "a gang" in Gaza City in a security campaign launched after a ceasefire came into effect on Friday, while six of its personnel were also killed in the violence, a Palestinian security source said on Monday.

The official said the security operation in Gaza City had targeted members of a "dangerous gang affiliated with a family in Gaza City." The operation had led to the arrest of 24 people and 30 others being wounded, the official said.

Since the ceasefire in the two-year-long war with Israel, the Hamas-run Interior Ministry in Gaza has deployed security forces in what it has described as an effort to prevent a security vacuum that would be filled by lawlessness and looting.

While President Donald Trump has demanded Hamas disarm under a plan to end the Gaza war, he indicated that it had a green light for internal security operations, saying they wanted "to stop the problems" and "we gave them approval for a period of time."

The official did not identify the gang involved, although there are several clans in Gaza which have long been seen as rivals to Hamas but who only emerged in more open opposition as the war ground on. There have been several clashes.

However, the official said the gang was not part of a group led by the most prominent anti-Hamas rebel, Yasser Abu Shabab, who is based in Rafah in southern Gaza, an area controlled by Israel.

Hamas has accused Abu Shabab and his supporters of being collaborators with Israel. He denies receiving Israeli support or having contacts with the Israeli army.

The Hamas security official said a senior aide to Abu Shabab "has been liquidated" since the security campaign started with the ceasefire, and said the hunt for Abu Shabab was underway.

"The security campaign is continuing and escalating until this issue is completely over, and no party will be allowed to violate the law," he added.