GAZA STRIP - Nizaar Rian, a senior Hamas leader in Gaza, told supporters Thursday diplomacy with Israel was a “failure” and encouraged them to redouble efforts to “liberate” Palestine. “All of Palestine, from the river to the sea, will be liberated by the mujhadeen (martyrs) and their rifles, not by pointless diplomatic meetings,” he said. Riad's comments are part of a sharp rhetorical offensive by Hamas leaders in recent days. The group has warned the temporary calm is falling apart, a message echoed by Islamic Jihad and the al-Aqsa Martyrs' Brigades. Brigade members also staged an armed march in Gaza. Losing control Palestinian Authority officials that without significant political developments soon, they are in danger of losing control of Gaza. But even now, it appears the Authority is having difficulty. Thursday, a Palestinian policeman was killed by a wanted Aqsa Brigades member in Jenin, and masked gunmen fired on a motorcade carrying Prime Minister Ahmed Qurei near a refugee camp in Nablus. The incident occurred after Palestinian police arrested a Brigades member, Sa'ad Amin, on suspicion of shooting a Palestinian legislator following a dispute. Amin was released after questioning, but returned to the police station later and opened fire. Palestinian security chiefs gathered in Jenin to discuss the incident. Amin has not been re-arrested, and the al-Aqsa Martyrs' Brigades has denied any connection to the incident. Heights of anarchy The incident displays the Palestinian Authority’s growing difficulty asserting its authority over armed elements in Gaza, despite promises by Chairman Mahmoud Abbas and Palestinian police chief Aleh Hosni that lawbreakers would be dealt with severely and quickly. Hosni also admitted in recent days that anarchy in the Authority has reached new heights. This week, American, Israeli and Egyptian officials have pushed Abbas to put an immediate end to the deteriorating security situation in the Territories.