Hamas is preventing human rights lawyers from visiting dozens of Palestinians arrested in the group's recent crackdown on Fatah supporters in the Gaza Strip, Reuters quoted a human rights group as saying Thursday. The arrests followed a July 25 bombing that killed five members of Hamas's armed wing and a seven-year-old girl. Fatah denied involvement in the attack and in response to the Hamas arrests, embarked on crackdown of their own, against Hamas members in the West Bank. Altogether, more than 250 Palestinians were arrested by both Hamas and the Fatah-dominated PA security forces since the explosion. The Gaza-based Palestinian Center for Human Rights (PCHR) said the detentions were illegal and that several of the arrests had been carried out by Hamas's armed wing, Izzadin Kassam, without warrants. PCHR director Raji Sourani told Reuters that his lawyers had been blocked from visiting any of those detained by Hamas for political reasons. The PCHR, citing testimony from victims, also said that Hamas was abusing and torturing some detainees. Hamas spokesman Sami Abu Zuhri said Thursday that the PCHR report was "unfair and unbalanced," adding that it ignored the arrest campaign by forces loyal to Palestinian Authority President Mahmoud Abbas against Hamas activists in the West Bank.