Hamas said on Saturday that it would fight against Israeli soldiers that Olmert said they would still remain in Palestinian territories despite its "unilateral ceasefire" in the Gaza Strip.
"A unilateral ceasefire does not mean ending the (Israeli) aggression and ending the siege. These constitute acts of war and so this will not mean an end to resistance," Hamas spokesman Fawzi Barhoum told Reuters in Gaza.
He also slammed Israel for taking a unilateral approach rather than entering into a deal with Egyptian mediators: "It is an attempt to pre-empt the Egyptian efforts and any other efforts that seek to achieve a withdrawal of the occupying forces, an end to the siege and a ceasefire."
Hamas wants Israel to lift a blockade on trade with Gaza and to withdraw the troops which occupied the territory on Jan. 3.
Israel said it would cease fire from 2 a.m. (0000 GMT) on Sunday. Israeli Prime Minister Ehud Olmert announced the planned ceasefire.
Other Palestinian resistance groups in the Gaza Strip rejected Israel's ceasefire.
Olmert said that Israeli troops will remain in Palestinian territory despite ceasefire.
Islamic Jihad said in a statement that "the resistance will continue its battle as long as occupation forces are on the land of Gaza and as long as the siege and the blockade continue."
Abu Youssef Said, a spokesman for the Popular Resistance Committees, said: "A unilateral ceasefire is nothing to do with us ... and we will continue to bear arms."
Hamas's representative in Lebanon, Osama Hamdan, told Al Jazeera: "If the Israeli military continues its existence in the Gaza Strip, that is a wide door for the resistance against the occupation forces."
PHOTO CAPTION
Trails of smoke are seen after the launch of rockets from the northern Gaza Strip towards Israel January 18, 2009.
Reuters