Turkey is allowing Hamas to plan attacks on Israel from Istanbul, according to a report in the Daily Telegraph on Wednesday.
An attempt to assassinate Jerusalem Mayor Nir Barkat earlier this year had been one of the operations plotted from Turkish soil, the paper said.
Both Turkey and Hamas denied the allegations, which are based on transcripts of Israeli police interrogations of suspects.
But an Israeli foreign ministry spokesman said: “Israel is extremely concerned that Turkey is allowing Hamas terrorists to operate from its territory, in planning and engaging in terrorist attacks against Israeli civilians.”
While Hamas is proscribed in the European Union, it is believed to still maintain offices in Turkey. The Palestinian group’s political leader Ismail Haniyeh met Turkish President Recep Tayyip Erdogan in Istanbul at the weekend.
Israel says Turkey has failed to abide by a 2015 agreement to prevent Hamas using its territory to plot attacks against Israel.
The Telegraph said a number of senior Hamas figures have settled in Turkey from Gaza over the past year, including one former leader of a suicide bomb squad.
According to the transcript, one Hamas operative in Turkey tried to encourage suicide attacks in Israel by offering $20,000 (£15,250) to the family of any bomber
But the group claimed it carried out activities “only in the land of occupied Palestine”.