TIMELINE: Israeli-Hamas violence since ceasefire ended

(Reuters) - Palestinian militants in the Gaza Strip launched rockets into southern Israel on Sunday in defiance of the unilateral ceasefire that Israel declared hours earlier and which Hamas pledged to ignore.

Here is a timeline of events since a six-month ceasefire between Israel and Hamas in the Gaza Strip ended last month.

December 19, 2008 - Ceasefire expires.

December 24 - Gaza Palestinian militants fire rockets at Israel.

December 27 - Israel launches air strikes on Gaza in response to the rocket and mortar fire, killing at least 229 Palestinians.

December 28 - Israeli air strikes hit the Islamic University and target smuggling tunnels in the Gaza Strip.

December 31 - Emergency U.N. Security Council session on Arab resolution calling for ceasefire adjourns without a vote.

January 1, 2009 - Israel kills Nizar Rayyan, a hardline Hamas leader, in an air attack on his Gaza Strip home.

January 3 - Israel launches a ground offensive in the Gaza Strip, sending tanks and infantry into battle with Hamas.

January 4 - Israelis cut the strip in half from the border fence to the Mediterranean. Troops and armor ring Gaza City.

January 5 - French President Nicolas Sarkozy, on a peace mission, and U.S. President George W. Bush, call for ceasefire.

January 6 - Israeli shelling kills 42 Palestinians at a U.N. school in Jabalya refugee camp where civilians had sheltered.

-- Egypt, backed by France and other European powers, proposes an immediate ceasefire.

January 7 - Israel says it views "positively" talks with Cairo over a wider ceasefire plan promoted by Egyptian President Hosni Mubarak and Sarkozy.

January 8 - Rockets fired from Lebanon strike northern Israel, wounding two people.

-- The U.N. Security Council votes for a resolution calling for an immediate ceasefire in Gaza, but the United States abstains, citing Egyptian-mediated talks on a truce.

-- The U.N. Relief and Works Agency (UNRWA), which distributes the majority of aid in Gaza, suspends its operations after an Israeli tank shell kills an UNRWA driver in a convoy.

January 9 - Israeli Prime Minister Ehud Olmert rejects the U.N. resolution as "unworkable" and, noting Palestinians fired rockets at Israel, says the army will go on defending Israelis.

January 10 - Hamas leader Khaled Meshaal accuses Israel of perpetrating a "holocaust" in Gaza and says his group will not consider a ceasefire until Israel ends its assault.

-- Palestinian President Mahmoud Abbas meets Mubarak in Cairo. Egypt later says it will not accept foreign troops on its side of the border with Gaza to stop arms smuggling.

January 11 - Israeli forces edge into the Gaza Strip's most populous area, throwing army reservists into battle.

-- Israel says stopping arms smuggling from Egypt to the Gaza Strip should be done by Egyptian forces and rejects the idea of an international force.

January 12 - Olmert, Israeli Defense Minister Ehud Barak and Foreign Minister Tzipi Livni decide against ordering troops in to engage in all-out urban warfare.

January 13 - Hamas says it has "substantial observations" about an Egyptian ceasefire proposal.

January 14 - Rockets fired from Lebanon strike Israel for the second time in a week.

-- U.N. Secretary General Ban Ki-moon arrives in Cairo and calls again for an immediate ceasefire between Israel and Hamas.

-- A Hamas delegation is holding talks with Egyptian intelligence officials on an Egyptian initiative, but Hamas has said changes to the Egyptian proposals are needed.

-- Human Rights Watch says Israel's daily three-hour break in attacks to facilitate the supply of humanitarian aid to Gazans is "woefully insufficient."

January 15 - Israeli forces push deeper into Gaza city unleashing their heaviest shelling in three weeks of war.

-- An Israeli envoy is to meet Egyptian mediators in Cairo after a Hamas delegation ends talks on Egyptian truce proposal.

-- UNRWA says its compound is struck twice by Israeli fire and three staff members are injured.

-- U.N. Secretary-General Ban Ki-moon tells Israel that the death toll from fighting has reached an "unbearable point."

January 17 - Israel declares unilateral ceasefire with effect from midnight (0000 GMT). Hamas guerrillas say the war will go on.

January 18 - Palestinian militants launch rockets into southern Israel in defiance of the ceasefire.