The operation by Turkey's spy agency and Istanbul counter-terror police showed the suspects had passed on information to Mossad for money, the Anadolu state news agency reported.

The raids come after Turkish authorities rounded up 34 people in January suspected of planning abductions and spying for Mossad.

Istanbul prosecutors had then said 12 other suspects remained at large.

After the January arrest, Erdogan said the Turkish operation "seriously disturbed" Israel.

"Wait a minute," he said, referring to the Israeli authorities. "You will get to know Turkey."

Relations between Turkey and Israel imploded after the outbreak of the Israeli war on Gaza nearly five months ago.

Turkish President Recep Tayyip Erdogan has turned into one of the world's harshest critics of Israeli Prime Minister Benjamin Netanyahu.

He said Netanyahu was no different from Adolf Hitler and likened Israel's attacks on Gaza to the treatment of Jewish people by the Nazis.

He also asked Israel's Western allies to drop their support for the "state terrorism" being conducted in Gaza.

Sharpening his rhetoric, Erdogan said Turkey would welcome academics and scientists facing persecution for their views on the conflict in Gaza, adding Western countries supporting Israel were complicit in war crimes.

"They used to speak ill of Hitler. What difference do you have from Hitler? They are going to make us miss Hitler. Is what this Netanyahu is doing any less than what Hitler did? It is not," Erdogan said.

Ankara says trade with Israel has fallen sharply since the war erupted.