Smoke rises after an Israeli air strike in Gaza Jan. 3, 2009. Israeli soldiers and Gaza militants exchanged fire in northern and eastern Gaza Strip on Saturday night, Gaza ruler Hamas said.

GAZA, Jan. 3 (Xinhua) -- Israeli soldiers and Gaza militants exchanged fire in northern and eastern Gaza Strip on Saturday night, Gaza ruler Hamas said.

The movement said in a statement that heavy exchange of fire and armed clashes took place between Gaza militants and Israeli ground forces which launched ground incursions into the densely populated enclave on Saturday night.

Hamas said fighters of al-Qassam Brigades, its armed wing, and other Palestinian factions are "confronting with the Israeli army ground forces, which entered the Gaza Strip territory early Saturday evening."

"The Israeli army forces are slowly entering the area because of the heavy gunfire of the Palestinian resistance," Hamas said, adding that "some Israeli soldiers are either killed or wounded."

The Israeli army was not available to confirm or deny Hamas reports on casualties among the Israeli soldiers. No injuries or fatalities were reported on the Palestinian side.

Earlier in the day, Hamas warned Israel against a large-scale military operation into the Gaza Strip which it has been ruling since June 2007.

Hamas armed wing, al-Qassam Brigades, said in a statement that "al-Qassam brigades declare that the Zionist enemy is getting close to the trap that our fighters had prepared for its soldiers and tanks."

The group said "the Zionist enemy would see surprises and would regret carrying out such an operation and will be a heavy price. Our militants are waiting with patience for confronting the soldiers face to face."

Israel began the ground operation following eight days of intensive warplanes air strikes on the enclave of 1.5 million population, targeting mosques, houses and security installations.

Israeli Televisions Channel I and II quoted an Israeli army spokesman as saying that the Israeli army began on Saturday night a ground operation into the Gaza Strip to rein in Palestinian militants who launch rockets at Israel on nearly a daily basis.

Palestinians living in northern and eastern Gaza Strip said they can hear engine sounds of Israeli tanks and armored vehicles, adding that columns of Israeli tanks stationed near the borders are preparing to enter.