Israeli air strikes on three houses in the southern Gaza city of Rafah have killed 13 people and wounded many others, medics say.
Hamas media outlets put the death toll at 15.
In Gaza City, in the north of the strip, Israeli planes struck two houses, killing and wounding several people, health officials said.
Monday's strikes on Rafah, where over a million people are sheltering from months of Israeli bombardment, came hours before Egypt was expected to host leaders of the Islamist group Hamas to discuss prospects for a ceasefire agreement with Israel.
The war was triggered by an attack by Hamas militants on Israel on October 7, killing 1200 and taking 253 hostages, according to Israeli tallies.
Israel has vowed to eradicate Hamas, which controls Gaza, in a military operation that has killed more than 34,000 Palestinians, 66 of them in the past 24 hours, according to Gaza's health authorities.
The war has displaced most of the 2.3 million population and laid much of the enclave to waste.
Khalil Al-Hayya is leading a delegation of Hamas officials in ceasefire discussions with mediators. (AP PHOTO)
On Sunday, Hamas officials said a delegation, led by Khalil Al-Hayya, the group's deputy Gaza chief, would discuss a ceasefire proposal handed by Hamas to mediators from Qatar and Egypt, as well as Israel's response.
Mediators, backed by the US, have stepped up their efforts to conclude a deal as Israel threatened to invade Rafah.
Two Hamas officials who spoke to Reuters did not disclose details of the latest proposals, but a source briefed on the talks told Reuters Hamas is expected to respond to Israel's latest truce proposal delivered on Saturday.
The source said this included an agreement to accept the release of fewer than 40 hostages in exchange for releasing Palestinians held in Israeli jails and to a second phase of a truce that includes a "period of sustained calm" - Israel's compromise response to a Hamas demand for a permanent ceasefire.
After the first phase, Israel would allow free movement between south and north Gaza and a partial withdrawal of Israeli troops from Gaza, the source said.
A senior Hamas official told Reuters the Monday talks in Cairo will take place between the Hamas delegation and the Qatari and Egyptian mediators to discuss remarks the group has made over the Israeli response to its recent proposal.
"Hamas has some questions and inquiries over the Israeli response to its proposal, which the movement received from mediators on Friday," the official told Reuters.
Those comments suggested Hamas may not hand an instant response to mediators over Israel's latest proposal.