Russian President Vladimir Putin said on Friday an Israeli ground offensive in Gaza would result in a level of civilian casualties that would be "absolutely unacceptable."
Putin was speaking after Israel's military called for all civilians of Gaza City - more than 1 million people - to relocate south within 24 hours, as it amassed tanks ahead of an expected ground invasion in response to a devastating weekend attack by the Islamist militant group Hamas.
He said there had been calls even in the United States for a blockade of the Hamas-controlled Gaza Strip on a par with "the siege of Leningrad during World War II."
"In my view it is unacceptable," Putin told reporters at a summit in Kyrgyzstan. "More than 2 million people live there. Far from all of them support Hamas by the way, far from all. But all of them have to suffer, including women and children. Of course it's hard for anyone to agree with this."
His criticism of Israel was made all the more stinging by the reference to the 1941-44 siege of Leningrad and the implied comparison between Israel and Hitler's Germany, with potential for causing deep offense in Israel.
Putin: Israel has right to defend itself
Putin said, however, that Israel had the right to defend itself after being subjected to "an attack unprecedented in its cruelty."
He called for collective efforts to secure an early ceasefire and stabilize the situation on the ground.
"Russia is ready to coordinate with all constructively minded partners," Putin said.
He said negotiations should be directed towards a two-state solution of the Middle East conflict in which Palestinians would get their own state with East Jerusalem as its capital.
Putin repeated previous criticism of the United States, saying the current tragedy was the outcome of the failure of US policy in the Middle East.
Russia has longstanding ties to both Israel and the Palestinians, including Hamas, but its relations with Israel have come under strain since the start of the Ukraine war.
On Thursday, Moscow urged Israel to agree to a ceasefire to allow food and medicine into Gaza and said it was unacceptable that the "indiscriminate" bombing of the small, blockaded coastal territory was causing so many civilian casualties.
The Russian Foreign Ministry said a deputy minister, Mikhail Bogdanov, met the Lebanese ambassador to Moscow on Friday to discuss the crisis.
It said their conversation emphasized "the inadmissibility of the spread of armed confrontation to Lebanon and other states in the region, the danger of a growing humanitarian crisis and a new massive influx of Palestinian refugees."