Israel's government on Sunday warned against travel to Turkey after three of its citizens were murdered in an Istanbul suicide bombing the previous day.
The country's anti-terrorism office raised its threat assessment and "recommends avoiding visits to Turkey," it said in a statement.
"Yesterday's deadly attack in Istanbul, in which a group of Israeli tourists was hit, underscores the threat against tourist targets throughout Turkey."
Tens of thousands of Israelis visit nearby Turkey each year despite strained diplomatic relations between the two countries.
Besides the three murdered, another ten Israelis were wounded, foreign ministry spokesman Emmanuel Nahshon said.
Five lightly wounded Israelis were flown home overnight, medics said Sunday. The army said the five others with more serious injuries and the bodies of those killed were returned by Israel's military on Sunday afternoon.
The three Israelis murdered were identified as Avraham Goldman, 69, Yonatan Suher, 40, and Simha Damari, 60. They were part of a group of Israeli tourists on a culinary-themed trip to Turkey.
Saturday's blast in the heart of Istanbul also killed an Iranian. Turkey said the attack was linked to the Islamic State jihadist group.
Prime Minister Binyamin Netanyahu has said he had no evidence that the attack targeted Israelis, although deputy director of the World Zionist Organization Ya'akov Hagoel told Arutz Sheva on Sunday that the terrorist targeted Jews.
The attack came six days after a suicide car bombing at a busy square in the capital Ankara that killed 35 people and was claimed by Kurdish rebels.
NATO member Turkey was a key regional ally of Israel until the two countries fell out in 2010 over the infamous Mavi Marmara flotilla, which sought to breach Israel's legal blockade on Gaza. IDF soldiers were forced to open fire to defend themselves after being attacked with knives and metal bars on the ship, and in the process they killed ten radical Islamist activists.
There have been diplomatic efforts in recent months to normalize ties.
On Sunday, the director general of the Israeli foreign ministry Dore Gold arrived in Istanbul for meetings with Turkish officials and local Jewish leaders as well as Israeli diplomats, his office said.
Gold is a close confidant of Netanyahu, and his visit to Turkey is the first by a high-ranking Israeli official in years.
AFP contributed to this report.