- Defence minister says achieving Israel's objectives won't be quick or easy
- UN Secretary General visits Egypt's crossing to Gaza
- Guterres: aid trucks need to move as soon as possible
- At least 4,137 Palestinians reported killed
The Secretary General of the United Nations visited the crossing between the besieged Gaza Strip and Egypt, and said humanitarian aid must be allowed across as soon as possible.
Israel has been relentlessly pounding Gaza with air strikes and it put the enclave's 2.3 million people under a total siege, banning even shipments of food, fuel and medical supplies.
At least 4,137 Palestinians have been killed, including hundreds of children, and 13,000 wounded in Gaza, the Palestinian health ministry said.
The UN says more than a million have been made homeless.
Israeli Defence Minister Yoav Gallant, who told troops the previous day that an order to invade would come soon, said on Friday that achieving Israel's objectives would not be quick or easy.
"We will topple the Hamas organisation. We will destroy its military and governing infrastructure. It's a phase that will not be easy. It will have a price," he told a parliamentary committee.
He added that the subsequent phase would be more drawn out, but was aimed at achieving "a completely different security situation" with no threat to Israel from Gaza. "It's not a day, it's not a week, and unfortunately it's not a month," he said.
The Orthodox Patriarchate of Jerusalem, the main Palestinian Christian denomination, said that overnight Israeli forces had struck the Church of Saint Porphyrius in Gaza City, where hundreds of Christians and Muslims had sought sanctuary.
It said targeting churches that were used as shelters for people fleeing bombing was "a war crime that cannot be ignored".
Video from the scene showed a wounded boy being carried from rubble at night. A civil defence worker said two people on upper floors had survived; those on lower floors had been killed and their bodies were still in the rubble.
"They felt they would be safe here. They came from under the bombardment and the destruction, and they said they would be safe here but destruction chased them," a man cried out.
Gaza's Hamas-run government media office said 18 Christian Palestinians had been killed, while the health ministry later gave a toll of 16.
The Israeli military said part of the church was damaged in a strike by fighter jets on a nearby Hamas command centre involved in launching rockets and mortars towards Israel, and that it was reviewing the incident.
Israel has already told all civilians to evacuate the northern half of the Gaza Strip, which includes Gaza City. Many people have yet to leave saying they fear losing everything and have nowhere safe to go with southern areas also under attack.
In Zahra, a northern Gaza town, residents said their entire district of some 25 apartment buildings was razed.
They received Israeli warning messages on their mobile phones at breakfast, followed 10 minutes later by a small drone strike. After another 20 minutes, F-16 warplanes brought the buildings down in huge explosions and clouds of dust.
"Everything I ever dreamt of and thought that I have achieved was gone. In that apartment was my dream, my memories with my children, and my wife, was the smell of safety and love," Ali, a resident of the district, told Reuters by phone.
The United Nations humanitarian affairs office said more than 140,000 homes - nearly a third of all homes in Gaza - have been damaged, with nearly 13,000 completely destroyed.
The south of the enclave has also been regularly hit. Rescue workers were combing through the wreckage of a house in the main southern city, Khan Younis, for survivors. One carried the limp body of a child.
"We don't want to receive aid, we want the destruction and the killing of children in their sleep to stop. We are tired," said neighbour Joumana Khreis.
A man wept while a medic comforted him at the side of a road next to two dead bodies wrapped in white shrouds. The bodies were later held aloft by marchers who carried them through the Khan Younis streets.
International attention has focused on getting aid to Gaza through the one access point not controlled by Israel, the Rafah crossing to Egypt. US President Joe Biden, who visited Israel on Wednesday, emerged with a promise from Israel to allow limited shipments from Egypt provided the aid is monitored to prevent any reaching Hamas.
UN Secretary-General Antonio Guterres toured the checkpoint on Egypt's side and called for a meaningful number of trucks to enter Gaza every day and checks to be quick and pragmatic.
