Antony Blinken speaks to members of the press at David Kempinski Hotel in Tel Aviv on Monday. AFP

Secretary of State Antony Blinken on Monday urged Hamas to accept a US bridging proposal for a Gaza ceasefire and hostage release deal after what he said was a "very constructive" meeting with Israeli Prime Minister Benjamin Netanyahu.

He had earlier said the latest push for a deal was probably the best and possibly last opportunity, urging both sides towards agreement.

Blinken said he will travel on Tuesday to Qatar, the key mediator with Hamas, after stops in Israel and Egypt to push forward a ceasefire proposal.

Egypt and Qatar "are our two critical partners in this effort to get the ceasefire agreement over the finish line, to get the hostages home, to put everyone on a better path to lasting peace and security," Blinken told reporters in Tel Aviv on Monday.

Talks in Qatar last week paused without a breakthrough, but the negotiations are expected to resume this week based on the US proposal to bridge the gaps between Israel and Hamas.

"In a very constructive meeting with Prime Minister Netanyahu today, he confirmed to me that Israel accepts the bridging proposal — that he supports it," Blinken told reporters in Tel Aviv.

"It's now incumbent on Hamas to do the same, and then the parties, with the help of the mediators — the United States, Egypt and Qatar — have to come together and complete the process of reaching clear understandings about how they'll implement the commitments that they've made under this agreement."

Despite US expressions of optimism and Netanyahu's office describing the meeting as positive, both Israel and Hamas have signalled that any deal will be difficult.

Hamas accused Netanyahu on Sunday of "thwarting the mediators' efforts" and Turkey said Hamas envoys had told it that US officials were "painting an overly optimistic picture."

Late on Sunday, Hamas said in a statement that Netanyahu has continued to set obstacles to a deal by demanding new conditions, accusing him of wanting to prolong the war. It said the mediators’ latest offer was a capitulation to Israel. "The new proposal responds to Netanyahu’s conditions,” Hamas said.

Months of on-off talks have circled the same issues, with Israel saying the war can only end with the destruction of Hamas as a military and political force and Hamas saying it will only accept a permanent, and not a temporary, ceasefire.

There are disagreements over Israel's continued military presence inside Gaza, particularly along the border with Egypt, over the free movement of Palestinians inside the territory, and over the identity and number of prisoners to be freed in a swap.

POLIO VACCINATION DRIVE

Meanwhile, Blinken said that Israel has agreed to support efforts to vaccinate Gazans for polio after the besieged territory reported its first case of the disease in 25 years.

"We're working with the Israeli government on that, and I believe that we'll be able to move forward with a plan to do that in the coming weeks," Blinken told reporters. "It is urgent. It is vital," Blinken said.

The United Nations has said it already has detailed plans in place to vaccinate children across the Gaza Strip and could start this month.

However, that would require a pause in the fighting and Secretary-General Antonio Guterres has called for two seven-day breaks in the Gaza war to vaccinate the territory's more than 640,000 children.

Blinken, who did not say how the vaccination would take place, said he had a "detailed" discussion on the humanitarian situation in Gaza with Defence Minister Yoav Gallant.

"We very much share the concern about the possibility of its (polio's) reemergence, and we've been working on a detailed plan to make sure that those who need to be vaccinated against it can get vaccinated," Blinken said.

BRITISH DIPLOMAT QUITS

A British diplomat based in Ireland resigned over arms sales to Israel with his email circulated online saying the UK's foreign office "may be complicit in war crimes," it emerged on Monday.

Images of his resignation email sent to colleagues were posted online, with Mark Smith, who was based in the British embassy in Dublin, writing there was "no justification for the UK's continued arms sales to Israel."

Smith, who describes himself as an expert in arms sales policy, was a second secretary dealing with "counter terror," a relatively junior position in the foreign office (FCDO).

Issuing a follow-up statement, Smith said he had "written to the foreign secretary informing him of my resignation and urging him to urgently review the UK approach to the situation in Gaza", according to the BBC on Monday.

"Each day we witness clear and unquestionable examples of war crimes and breaches of international humanitarian law in Gaza perpetrated by the State of Israel," Smith wrote in the resignation email.

Agencies