Hamas has said an Israeli offer to extend a humanitarian ceasefire in Gaza is unacceptable because it does not include provision for the withdrawal of Israeli troops and for residents in the enclave to return to their homes.
Israel's security cabinet had earlier approved extending the ceasefire, which begun early on Saturday, until midnight local time (21:00 GMT) on Sunday, but warned it would respond to any fire from Gaza during this period and that it would continue to target tunnels used by Hamas and other groups.
"At the request of the United Nations, the cabinet has approved a humanitarian hiatus until tomorrow [Sunday[ at 24:00. The IDF [Israel Defence Forces] will act against any breach of the ceasefire," an Israeli official said in a statement.
Sami Abu Zuhri, a Hamas spokesman in Gaza, told Al Jazeera: "Any humanitarian ceasefire that doesn't include the complete withdrawal of its positions in the Gaza Strip, doesn’t enable the residents to go back to their homes and doesn’t allow the evacuation of the wounded, is unacceptable."
At least 20 rockets were fired from Gaza overnight, and air raid sirens sounded throughout southern and central Israel during morning rush hour. At least five rockets landed in Israel and two others were intercepted by the Iron Dome missile defence system, the military said.
There were no immediate reports of injuries.
An earlier extension of the ceasefire, until midnight local time on Saturday, was broken shortly after 8pm local time, with the Israeli military announcing three mortar rounds had been fired from Gaza into southern Israel.
Al Jazeera's Stefanie Dekker, reporting from Gaza, said she had been told there was no agreement among Palestinian factions in Gaza on extending the ceasefire.
"We've had it confirmed that al-Qassam Brigades [the military wing of Hamas] has fired rockets at Israel," she said.
After the ceasefire began early on Saturday, Gazans took advantage of the lull in fighting to retrieve their dead and stock up on food, flooding into the streets to discover scenes of massive destruction in some areas.
At least 1,049 Palestinians, mostly civilians, have been killed and more than 6,000 injured since Israel launched its offensive on the Mediterranean enclave, home to 1.8 million Palestinians, on July 8.
Israel said five more of its soldiers were killed in pre-truce fighting in Gaza and two others died of their wounds in hospital. Another soldier was killed by shell fire overnight, bringing the army death toll to 43.
Three civilians, including two Israeli citizens and a Thai labourer, have been killed by rockets fired from Gaza.