Sir Keir Starmer is expected to announce the UK's recognition of a Palestinian state in a statement on Sunday afternoon.
The prime minister said in July that the UK would shift its position unless Israel met several conditions, including agreeing to a ceasefire in the Gaza Strip and committing to a long-term peace process leading to a Palestinian state co-existing alongside Israel.
The Israeli leadership has ruled this out since the start of the war following Hamas's attack in southern Israel on 7 October 2023 in which 1,200 people were killed and 251 taken hostage.
The PM's move has drawn fierce criticism from the Israeli government, families of hostages held in Gaza and some Conservatives.
Israeli Prime Minister Benjamin Netanyahu previously said recognition of a Palestinian state "rewards terror".
The decision to recognise a Palestinian state represents a major change in UK foreign policy, after successive governments said recognition should come as part of a peace process and at a time of maximum impact.
However, ministers argue there was a moral responsibility to act to keep hopes of a long-term peace alive.
Efforts to secure a ceasefire in Gaza - let alone a long-term solution to the Israel-Palestine conflict - have faltered. Israel recently sparked international outrage when it carried out an air strike on a Hamas negotiating team in Qatar.
Government sources said the situation on the ground had also worsened significantly in the last few weeks. They cited images showing starvation and violence in Gaza, which Sir Keir previously described as "intolerable".
Israel's latest ground operation in Gaza City, described by a UN official as "cataclysmic", has forced hundreds of thousands of people to flee.
It is the latest Israeli offensive in the nearly two-year war which has seen much of the Palestinian territory's population displaced, its infrastructure destroyed, and at least 65,208 people killed, according to Hamas-run health ministry figures.
Earlier this week, a United Nations commision of inquiry concluded Israel had committed genocide against Palestinians in Gaza, which Israel denounced as "distorted and false".
Ministers have also highlighted the continued expansion of Israeli settlements in the occupied West Bank, which are illegal under international law, as a key factor in the decision to recognise Palestinian statehood.
Justice Secretary David Lammy, who was foreign secretary when recognition was proposed, cited the controversial E1 settlement project - which critics warn would put an end to hopes for a viable, contiguous Palestinian state - as well as violence from Israeli settlers in the West Bank.
BBC