More than 150 Palestinians were killed and hundreds were wounded on Friday as Israel resumed shelling after declaring a planned 72-hour Gaza ceasefire over, saying Hamas militants breached the truce soon after it took effect.

The armed wing of the Palestinian Islamist group Hamas said on Saturday it had no clear indication on the whereabouts of an Israeli soldier that Hamas has been accused of abducting in the Gaza Strip, adding he may have been killed during an ambush.

Israel said Second Lieutenant Hadar Goldin, 23, who went missing on Friday, had been abducted by Hamas gunmen.

The ceasefire lasted only about 90 minutes early on Friday.

A latest signal that the ceasefire was over came at daybreak when Israel's Iron Dome interceptor system shot down two militant rockets over the Tel Aviv area and a third over Beersheba.

Israeli Prime Minister Benjamin Netanyahu called his security cabinet into special session and warned Hamas and other militant groups they would "bear the consequences of their actions". No announcement was made after the meeting.

But a statement by Hamas's armed wing said it had no contact with militants who were operating in the southern Gaza Strip where Israel said Goldin went missing.

"We have lost contact with the group of fighters that took part in the ambush and we believe they were all killed in the (Israeli) bombardment. Assuming that they managed to seize the soldier during combat, we assess that he was also killed in the incident," the statement said.

The planned 72-hour break in fighting announced by US Secretary of State John Kerry and UN Secretary-General Ban Ki-moon hours before it was due to take effect early on Friday was the most ambitious attempt so far to end more than three weeks of fighting.

At least 1,592 Gazans have been killed since the start of hostilities on July 8 when Israel launched its drive to halt militant rocket fire on its territory from the coastal enclave by unleashing air and naval bombardments. Tanks and infantry pushed into the territory of 1.8 million people on July 17.

Sixty-three Israeli soldiers have been killed, and Palestinian rockets have killed three civilians in Israel.

US President Barack Obama called for the soldier's unconditional release and said it would be tough to reinstate a truce after the day's events.

"I think it's going to be very hard to put a ceasefire back together again if Israelis and the international community can't feel confident that Hamas can follow through on a ceasefire commitment," he told a White House news conference.

Obama said he has been in constant contact with Netanyahu about the situation, and added that more needed to be done to protect Palestinian civilians. - Reuters