A source close to Hamas earlier said talks were underway for the release of a dozen captives, including six Americans, in return for a three-day ceasefire in Gaza.

"I'd like to put to rest all kinds of false rumours we're hearing from all kinds of directions, and reiterate one clear thing: there will be no ceasefire without the release of our hostages," Netanyahu said.

Earlier Wednesday, a separate source briefed on the talks said Qatar was mediating negotiations in coordination with the US to free 10-15 captives in exchange for a one- to two-day ceasefire.

Qatar has been engaged in intense diplomacy to secure the release of those held by Hamas, negotiating the handover of four hostages; two Israelis and two Americans, in recent weeks

The G7 grouping of economically advanced nations called Wednesday for "humanitarian pauses and corridors" in the Israeli war on Gaza, but refrained from calling for a ceasefire, during talks in Japan.

An alliance of 13 major aid groups urged world leaders Wednesday to push for a ceasefire in Gaza, after one month of the Israeli war on the strip that has killed and injured more than 35,000 Palestinians and triggered one of the worst human catastrophes in the 21st century.