A dozen Fatah gunmen who had agreed to serve jail time in exchange for getting taken off Israel's wanted list escaped from a Palestinian Authority prison in Nablus late Friday, charging that guards beat them. The 12 members of the Aksa Martyrs Brigades fled after masked guards at the Jneid Prison began to pummel them with clubs following a fight among the detainees, the escapees' leader, Mahdi Abu Ghazaleh, said by telephone to Palestinian reporters. Israel expressed concern over the men's escape. "It's clear that dealing effectively with terrorism by the PA government is an integral element in the peace process," an Israeli official told The Jerusalem Post. "These people escaping from jail is a matter of concern to Israel." A commitment by PA President Mahmoud Abbas to rein in gunmen and stop violence is a key part of the peace talks that were renewed at Annapolis late last year. Palestinian police would not discuss the escape. The men who fled were among several dozen gunmen who turned themselves into PA police in January after Israeli troops searched for them in an arrest raid. Such operations often erupt into deadly shootings. Members of the group that surrendered previously fled from the Jneid Prison, staying away for 35 days, but then turned themselves in again. Abu Ghazaleh said this time would be different. "We won't return," he said.