The statement came after the Izz al-Din al-Qassam Brigades said it had fired nearly 30 rockets and 61 mortars into Israel on Tuesday.
Last Mod: 24 Nisan 2007, 19:50
Abu Obaida, a spokesman for the brigades, told AFP: "The truce no longer exists.
"It's the Israeli enemy that has not respected it and now it's the turn of Palestinian groups," he said.
The attacks, which came as Israel observed its 59th anniversary, caused no damage or injuries.
They marked the first time that Hamas, the senior partner in the Palestinian coalition cabinet, claimed responsibility for launching rockets into Israel since a November 26 ceasefire took effect between the army and Palestinian fighters.
Abu Obaida said the firing of Tuesday's projectiles was a response to the death of nine Palestinians, two teenagers and five fighters among them, by Israeli troops over the weekend in the occupied West Bank and Gaza.
The deaths marked the bloodiest weekend of Israeli-Palestinian violence since the November truce and sparked calls for retaliation on the part of Palestinian armed groups.
Under the terms of the November ceasefire, the Israeli army withdrew troops from the Gaza Strip and Palestinian fighters there were supposed to halt rocket fire.
Until Tuesday, the truce has largely held despite violations by both sides.