Tel Aviv/Gaza  - Israel's unilaterally-declared cessation of hostilities in the Gaza Strip entered into effect at 2 am (0000GMT) Sunday, in accordance with the announcement of Prime Minister Ehud Olmert several hours earlier.

No troops will withdraw from the enclave but Olmert said Israel will not initiative any offensives in Gaza and troops would only fire if fired upon by Palestinian militants, as decided upon in a security cabinet.

The Islamic Hamas movement, against whom the three-week-long Israeli operation was directed, said they would not respect any ceasefire so long as Israeli troops remained in the Gaza Strip and the borders to the territory were opened.

Israel began its offensive, named Operation Cast Lead, with the declared objective of stopping rocket fire from Gaza, on December 27 with a large aerial campaign, which was extended to a ground operation on January 3, when troops entered the coastal strip.

At least 1,203 Palestinians were killed during the offensive, including over 400 children and 106 women, medical sources said.

Ten Israeli soldiers and three civilians also died.

Israel had also said that the campaign would aim to curtail smuggling operations into Gaza and shut down weapons supplies to militants. It bombed the southern Gaza Strip, near the border with Egypt, hundreds of times in the last 22 days.

Gabi Ashkenazi, the Chief of Staff, said in a military statement that the operation had not yet concluded.

Israel and Hamas do not talk to each other directly but go through Cairo, which had been pushing for a ceasefire based on a short-term "humanitarian" truce, followed by negotiations on a longer-term ceasefire that would include the Israeli security concerns and the militants' demand that the borders be opened.

Egypt had earlier called for a ceasefire and a withdrawal of Israel's troops.

While Olmert said he responded positively to the calls, the troops were only likely to leave once Israel's key demands, the end of the rockets and smuggling, were met. (dpa)