GAZA CITY — The 27-year-old in a sweatsuit limped to the table, heaved himself into a chair and began to talk about how he had been shot. Men from Hamas have begun to assault people they suspect of supporting its chief political rival, Fatah, he said, and on Sunday, he became one of the victims.

It was impossible to verify the man’s account, which he provided on the condition that he remain anonymous, out of concern for his safety. But it came during a week in which leaders of Fatah accused Hamas of harassing and harming its members in the Gaza Strip.

Yasser Abd Rabbo, an ally of the Palestinian president, Mahmoud Abbas, said at a news conference in Ramallah on Thursday that Hamas had “turned its rifles in the direction of Fatah members” after Israel stopped its military offensive on Sunday. Mr. Rabbo accused Hamas of placing Fatah supporters under house arrest and shooting some of them in the legs, an intimidation tactic that it used in the past.

A Hamas spokesman, Fawzi Barhoum, strongly denied the accusation, saying that Fatah was raising the issue to distract attention from the fact that it remained on the sidelines and did not challenge Israel during the three weeks of fighting in Gaza.