KYIV (Reuters) -Israel needs a clear and concrete plan for the future of Gaza where it faces the potential for a power vacuum that could become filled by chaos, U.S. Secretary of State Antony Blinken said on Wednesday.

The remarks drew an apparent Israeli riposte, with Prime Minister Benjamin Netanyahu saying post-war planning was impossible without first completing the demolition of Hamas.

Washington and Israel agree that Hamas cannot continue to run Gaza after the Palestinian Islamist group's gunmen ignited the conflict with a cross-border killing and kidnapping spree last October.

But the allies are at odds over Israel's quest for "total victory" over Hamas, including in the southern city of Rafah, where the United States has warned against any major operation that might endanger displaced Palestinians massing there.

"We do not support and will not support an Israeli occupation. We also of course, do not support Hamas governance in Gaza ... We've seen where that's led all too many times for the people of Gaza and for Israel. And we also can't have anarchy and a vacuum that's likely to be filled by chaos," Blinken said during a press conference in Kyiv.

The U.S. top diplomat has held numerous rounds of talks with Israel's Arab neighbours on a post-war plan for Gaza. Israel says it intends to keep overall security control and has balked at proposals for the Palestinian Authority (PA), which wields limited rule in the Israeli-occupied West Bank, to take charge.

"It's imperative that Israel also do this work and focus on what the future can and must be," Blinken said. "There needs to be a clear and concrete plan, and we look to Israel to come forward with its ideas."

In a statement, Netanyahu appeared to push back against the criticism, though he did not refer directly to Blinken.

Israel, he said, has sought out Palestinians not aligned with Hamas to take charge of local civic management in Gaza - only to see them deterred by threats of Hamas retaliation.

"All the talk about 'the day after', while Hamas remains intact, will remain mere words devoid of content," Netanyahu said. "Contrary to what is being claimed, for months we have been engaged in various efforts to resolve this complex problem. Some of the efforts are covert and it is good that this is so."

Citing widespread support among Palestinians for the Oct. 7 attack, Netanyahu said, in an apparent reference to the PA: "We will not allow them to establish a terrorist state from which they will be able to vigorously attack us."

(Reporting by Simon Lewis and Dan Williams; Editing by Andrew Heavens, Peter Graff and Hugh Lawson)

By Simon Lewis