Turkish security forces have arrested seven people on suspicion of passing information to the Israeli intelligence service Mossad, unnamed officials say.
The arrests came after a joint raid by police and officials from Turkey’s MIT intelligence agency in Istanbul and the western city of Izmir.
A month ago 34 people with suspected Mossad links were charged with spying.
Turkey’s president has warned Israel of “serious consequences” if it targets Hamas members on Turkish soil.
Turkey – unlike most Western countries and some Arab states – does not classify Hamas as a terrorist organisation.
There is strong support for the Palestinians in Turkey, with tens of thousands regularly attending rallies in Istanbul and other cities.
Ankara has as not yet made a formal statement about Friday’s arrests.
But media reports via unnamed officials say MIT discovered that Mossad was using private detectives to monitor, photograph and track suspected Hamas members.
In January Justice Minister Yilmaz Tunc said the 34 detainees were charged with “political or military espionage” on behalf of Israeli intelligence.
Mossad is believed to have recruited Palestinians and Syrian nationals living in Turkey as part of its operations.
Turkish President Recep Tayyip Erdogan has been involved in an increasingly bitter war of words with Israeli Prime Minister Benjamin Netanyahu since Israel’s war with Hamas began.
He has described Mr Netanyahu’s actions in Gaza as “genocide” and last month compared him to Hitler.
Israeli intelligence officials have vowed to target Hamas outside the Palestinian territories, including in Lebanon, Qatar and Turkey.
Israel launched its war against the Islamist group after its fighters crossed into Israel on 7 October and carried out a series of deadly attacks which led to the deaths of about 1,300 people.
Some 250 people were taken back to Gaza as hostages – with 105 subsequently released during a truce in November.