Hamas's security forces in the Gaza Strip have asked Fatah detainees to bring their own food and drink with them, Fatah officials said on Wednesday. The officials said that at least 500 Fatah supporters have been detained by Hamas security forces over the past few days in one of the biggest security crackdowns in recent years. Some of the Fatah activists who were summoned for questioning by phone before they were detained said Hamas security officers told them to bring their own food and drink. "The prisons in the Gaza Strip are so full that Hamas doesn't have enough money to feed all the detainees," said a Fatah official in Ramallah. "In many cases the detainees receive permission to call their families and ask for food and soft drinks." Hamas representatives in the Gaza Strip said the latest clampdown was a "routine" measure aimed at preserving law and order. But another Fatah official said that Hamas was deliberately targeting senior officials of the faction in the Gaza Strip, including former ministers, members of Fatah's "revolutionary council," former Fatah legislators and former commanders of the Palestinian Authority security forces. "In the past 24 hours, Hamas kidnapped 156 Fatah members in the Gaza Strip," the official said. "Another 210 Fatah members have been in Hamas prisons for months and years." A human rights group reported that Hamas security forces had arrested 515 Fatah supporters in the Gaza Strip since the beginning of the week and called on the movement's leadership to release all of them. The group said that most of the detainees were being banned from receiving family members or meeting with lawyers. PA President Mahmoud Abbas condemned the Hamas crackdown and called for the release of all the detainees. He pointed out that the arrests coincided with his decision to release hundreds of Hamas detainees from Fatah-controlled prisons in the West Bank. "When we arrest someone, we interrogate him quickly and if we don't find anything we release him," Abbas said. "We don't have a problem with anyone." Abbas said that the PA has "verified information" that Hamas has been planning terrorist attacks against senior PA officials. "We are following the situation very closely and when the appropriate time comes we will produce the evidence to the media," he added. "We have discovered tons of explosives and weapons cashes in residential neighborhoods in the West Bank."