Washington DC - Kamala Harris signaled a major shift in US Gaza policy Thursday, with the presidential hopeful telling Israeli Prime Minister Benjamin Netanyahu to seal a peace deal and insisting she would not be "silent" on the suffering in the Palestinian enclave.

Ripping up outgoing President Joe Biden's playbook of mostly behind-the-scenes pressure on Israel, the vice president said after meeting Netanyahu that it was time to end the "devastating" war.

"What has happened in Gaza over the past nine months is devastating. The images of dead children and desperate hungry people fleeing for safety, sometimes displaced for the second, third or fourth time," Harris told reporters.

"We cannot look away in the face of these tragedies. We cannot allow ourselves to become numb to the suffering and I will not be silent."

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The 59-year-old – now the presumptive Democratic presidential nominee after Biden said at the weekend he would not stand in November's election – said she pressed Netanyahu on the dire situation in the "frank" meeting.

She said she "expressed with the prime minister my serious concern about the scale of human suffering and Gaza, including the death of far too many innocent civilians."

"And I made clear my serious concern about the dire humanitarian situation there."

Harris also called for the establishment of a Palestinian state and went on to call on both him and Hamas to agree to a ceasefire and hostage release deal to end the war sparked by Hamas's October 7 attack on Israel.

"As I just told Prime Minister Netanyahu, it is time to get this deal done," she said.

Harris's outspoken comments were a stark contrast to the largely amiable greetings between Biden and Netanyahu earlier in the day, even if it masked months of tensions between the two men as well as questions over the US president's relevance.

"From a proud Zionist Jew to a proud Zionist Irish American, I want to thank you for 50 years of public service and 50 years of support for the State of Israel," Netanyahu said in tribute to Biden at the start of the Oval Office meeting.

"And I look forward to discussing with you today and working with you in the months ahead."

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Harris has been more outspoken on Gaza in the past than Biden and there had been speculation that she could adopt a tougher approach on Israel. Officials earlier denied there is any "daylight" between her and Biden.

The White House said Biden would tell Netanyahu there needed to be "compromise" for a deal after the Israeli premier gave a fiery speech to the US Congress on Wednesday in which he vowed "total victory" against Hamas.

"The president will be reaffirming for Prime Minister Netanyahu that he believes we need to get there, and we need to get there soon," spokesman John Kirby told reporters.