Istanbul football derby cancelled one day after deadly bombing attack
The decision came one day after a suicide bomber killed himself and four other people on the city's main shopping street, leaving Turkey reeling from the second such attack within a week.
"Due to security concerns based on information provided by the TFF, Istanbul council and police force, tonight's match has been postponed," a message read on Galatasaray's official Twitter page.
No new date has been announced for the game, which was to be played in Istanbul's Turk Telekom Arena, a 52,000-capacity stadium on the city's northern outskirts.
Officials have given no further details on the nature of the threat.
Prior to the announcement, local media had reported that the game would go ahead without the fans.
The Istanbul governorship said in a statement that it is taking particular care "after the events that have happened in the last few days in our city."
A police helicopter was circling the arena and television reports showed hundreds of fans already gathered to watch the game. They have since been asked to leave the venue.
The cancellation came just hours after the Turkish government blamed the Islamic State extremist group for Saturday's attack.
Interior Minister Efkan Ala identified the bomber as Turkish national Mehmet Ozturk, born in 1992 in Gaziantep in southern Turkey, which is near the border with Syria.
Five arrests have been made in connection with the attack, the minister said.
The identification was based on DNA tests, using a blood sample from a family member, state news agency Anadolu reported.
President Recep Tayyip Erdogan said the goal of the attacks had been to spread "fear and resignation."
Islamic State has so far not claimed responsibility for the attack.
In January, 12 tourists were killed by a suicide bomber in Istanbul in an attack the authorities blamed on Islamic State.
The largest terrorist attack in the country's history was in October, when 100 people were killed in a series of bombings in Ankara also blamed on Islamic State.
Three of the dead were Israelis, of who two held dual Israeli-US citizenship, while a fourth fatality was reportedly an Iranian national.
At least 39 people were wounded in the explosion near a shopping area on Istiklal boulevard, a busy thoroughfare in the centre of Istanbul just off Taksim Square.
Among the injured in the blast in Turkey's largest city and economic hub were 24 foreigners, the local government's office said.
The German embassy school in Istanbul was to remain closed on Monday, according to a letter from the school administration. The school is located near Istiklal street where the bombing took place.
German diplomatic missions and schools were closed last week in Istanbul and Ankara following what was described as a "concrete" terrorism threat, apparently from the Islamic State extremist group.
The Istanbul attack came as the country has already been on edge following a massive car bombing in Ankara on March 13 that killed 37 people.
That attack was claimed by the Kurdistan Freedom Falcons (TAK), a splinter group of the banned Kurdistan Workers' Party (PKK).
A similar attack last month in the capital left 30 dead and was also claimed by TAK.
