Egypt PM Hisham Qandil decries Gaza 'disaster'
Egypt's prime minister has condemned Israeli attacks on Gaza as a "disaster" during a short trip to the territory.
Hisham Qandil, who talked to Hamas leaders in his three-hour visit, said Israel's "aggression" must stop.
Israel mounted a huge assault overnight and Gaza militants continued to launch rockets. Air-raid sirens and an explosion were later heard in Tel Aviv.
At least 20 Palestinians and three Israelis have been killed since Israel began its offensive on Wednesday.
Militants and civilians, including at least five children, were among the Palestinian dead, Palestinian officials said.
Two Israeli women and a man died when a rocket fired from Gaza hit a building in the southern town of Kiryat Malachi on Thursday, Israeli officials said.
The Israeli army began an initial draft of 16,000 reservists on Friday, after the government authorised the call-up of 30,000.
However, the BBC's Jon Donnison in Gaza says there is not yet any sign of a ground offensive.
Mr Qandil visited the Council of Ministers building in Gaza City, and also a hospital treating those wounded in attacks.
"What I am witnessing in Gaza is a disaster and I can't keep quiet. The Israeli aggression must stop," he said.
But he insisted that Egypt would "spare no effort" in trying to broker a ceasefire.
Ties between Hamas and Egypt have strengthened since the election of Islamist President Mohammed Mursi earlier this year.
Hamas was formed as an offshoot of the Muslim Brotherhood, to which Mr Mursi belongs.
Israel had said it would pause the offensive during Mr Qandil's visit, if militants refrained from firing rockets.
But shortly after the prime minister arrived, Israeli and Palestinian officials accused each other of violating the temporary truce.
While Mr Qandil was at the hospital in Gaza, medical workers brought in the bodies of a man and a boy who officials said had been killed in an Israeli air strike moments earlier.
Ministry building wrecked
Explosions continued in Gaza throughout Thursday night, with huge blasts rocking Gaza City as dawn broke.
Witnesses said parts of the Hamas interior ministry building were destroyed in the overnight raids.
Israel said it had targeted dozens of rocket-launching facilities in the coastal territory.
In recent days, militants say they have fired more than 350 rockets from Gaza.
Israel said 130 rockets had been intercepted by its Iron Dome missile defence system.
UK Foreign Secretary William Hague called on both sides to "de-escalate" the situation and warned against a ground attack.
"When Israel has entered into ground invasions in other conflicts, that is when they have lost a good deal of international sympathy and support," he said.
In Tel Aviv on Thursday, residents took cover after air-raid sirens alerted them to a missile threat for the first time since the Gulf War in 1991.
The armed wing of Islamic Jihad said it had fired an Iranian-built Fajr-5 rocket, which has an estimated range of 75km (45 miles).
Israel said two missiles had landed near Tel Aviv, one hitting an uninhabited area and another which is believed to have landed in the sea.
Violence escalated after the killing by Israel of Hamas' military leader Ahmed Jabari on Wednesday following a surge in rocket attacks from Gaza.
Israel had repeatedly carried out air strikes on Gaza, as Palestinian militants fired across the border.