Turkish Prime Minister Recep Tayyip Erdogan slammed Israel as a "persecutor" on Saturday in the latest verbal volley since the Gaza offensive raised tensions between the regional allies, AP reported.

"Turkey has never, in its history, been on the side of persecutors, it has always defended the oppressed," Erdogan said without directly naming Israel in a speech in the central city of Kirsehir.

"Turkey has not hostility against any country, but ... we are against injustice," he said in the televised remarks.

Ties between the strategic allies began to sour in January when Turkey strongly condemned Israel's 22-day assault on the Gaza Strip, which was launched to counter rocket attacks by Palestinian militants.

Relations took another sharp downturn last week when Ankara excluded the Jewish state from annual joint military exercises, prompting a rebuke from the United States.

And in recent days, Israel criticised a Turkish state television series that depicts Israeli soldiers deliberately killing Palestinian children.

Turkish Foreign Minister Ahmet Davutoglu said Friday that relations would improve when the "humanitarian tragedy" in Gaza ends and Middle East peace efforts are revived.

Erdogan has been at the forefront of international criticism of the Gaza offensive.

In an unprecedented outburst, he stormed out of a debate at the World Economic Forum in January, accusing Israel of "barbarian" acts and telling Israeli President Shimon Peres, sitting next to him, that "you know well how to kill people."