The truce marks the biggest diplomatic breakthrough since the start of the war that has devastated vast swaths of Gaza and raised fears of a wider conflict across the Middle East.

Qatar, which has played a key role in mediating with Hamas, announced the deal without saying when it would go into effect. Fifty Israeli captives will be released in stages over the four days, in exchange for what Hamas said would be 150 Palestinian prisoners.

Both sides will release women and children first, and the supply of humanitarian aid flowing into the besieged territory will be ramped up.

Prime Minister Benjamin Netanyahu said Israel would resume the war after the truce and keep fighting “until we achieve all our goals,” including the defeat of Hamas.

Residents in Gaza City said the fighting there had intensified overnight into Wednesday, with gunfire, heavy artillery and airstrikes in central neighbourhoods.

“They are mad. Apparently, they want to advance before the truce,” said Nasser Al-Sheikh, who is sheltering with relatives in the Sheikh Radwan neighbourhood.

The announcement capped weeks of indirect Qatari-led negotiations between Israel and Hamas. The United States and Egypt were also involved in stop-and-go talks to free some of the roughly 240 captives captured by Hamas and other fighters during their wide-ranging 7 October operation.

President Joe Biden welcomed the deal, saying Netanyahu has committed to supporting an “extended pause” to make sure that the captives are released and humanitarian aid can be sent to Gaza.

Qatar’s top diplomat Prime Minister Sheikh Mohammed bin Abdulrahman Al Thani said he hoped the deal would eventually lead to a permanent cease-fire and “serious talks” on resolving the Israeli-Palestinian conflict.

The International Committee of the Red Cross said it is standing by to assist any swap.

Israel's Justice Ministry published a list of 300 prisoners eligible for release as part of the deal, mainly teenagers detained over the past year for rock-throwing and other minor offences. Under Israeli law, the public has 24 hours to object to any release.

Israel said that to facilitate the captives' release it would initiate a four-day "pause" in its six-week-old air, land, and sea assault of Gaza, while it stressed that the agreement did not spell the end of the war.

Qatar's Foreign Ministry Spokesman Majed Al-Ansari told AFP that it is expected that the truce will be extended by the release of further captives by Hamas.

"If by [the end of the four days] the Palestinians can commit to an additional number, then the truce can be extended," Al-Ansari said.

Israel said that the truce would be extended an extra day for every additional 10 captives released by Hamas.

"It will take some time to get all the civilians out within these parameters, it will take some time also to... ascertain how many we have left," Al-Ansari said.

The temporary cessation of hostilities would not come into effect immediately and would "need some time to be prepared on the ground," he said.

During the period captives are moved, Israeli reconnaissance of Gaza will be put on temporary hold, said the spokesman, who is also a key adviser to Qatar's prime minister.

Under the deal "there are no military prisoners among those to be released," he said, indicating that was an area where trust would have to be built if talks were to move forward.