"Israel is committing ethnic cleansing by ignoring peace in this region and violating international law," Erdogan said yesterday. "It is occupying the Palestinian territory step by step."
The premier said Israeli air raids against Gaza could not be deemed self-defence, accusing Western countries of aiding what he called a "terrorist state" by condoning its violence in the Middle East.
"Sooner or later, Israel will answer for the innocent blood it has shed so far," he said.
Erdogan's words came after Israel halted a threatened Gaza ground operation to give Egyptian-led truce talks a chance to end nearly a week of cross-border violence that has killed more than 100 Palestinians and three Israelis.
He said Turkey, Egypt and the Gulf countries, particularly Qatar and Saudi Arabia, had to take their own initiative, accusing the United Nations Security Council of
doing nothing to save Gazans.
"It is against them today, tomorrow it will be us, keep that in mind," he said. "If we are going to die, let's go down with decency. Keep that in mind too."
In Washington, the United States -- an ally of both Israel and Turkey -- was upset with the harsh words.
"Some of the extremely harsh rhetoric coming from Turkey we do not consider helpful at all," said State Department spokeswoman Victoria Nuland.
"Of course we don't agree with some of these very difficult statements that have been coming there. And we've made those views clear to the Turks," she said.
Nuland said that State Department officials have "made clear ... to the Turkish government our concerns that this kind of rhetoric is not helpful."
On Monday, Erdogan said the UN "turned a blind eye" on Israeli attacks against Palestinians, accusing the international body of double standards against Muslims.
Erdogan emerged as a staunch advocate of the Palestinian cause in January 2009, when he stormed out of a panel discussion on Israel's blockade of the impoverished Gaza Strip at the World Economic Forum in Davos.
Ties between Turkey and Israel were further strained after Israeli commandos raided a Gaza-bound Turkish aid flotilla in the Mediterranean in May 2010, killing nine Turks on board.