Interior Minister Efkan Ala told Haber 7 TV in an interview that three cars loaded with explosives to be used in attacks had been found by the authorities.
He indicated that one car was seized at Istanbul's Bogazici University last week which caused a major security alert on the campus.
"Since the start of the year, 18 suicide bombings have been prevented... We don't talk (to the public) about most of the prevented attacks," he said, without giving details on the nature of the plots.
In 2015, there were also four deadly bomb attacks blamed on Islamic State (IS) jihadists, including the deadliest in Turkey's modern history that killed 103 people in Ankara in October.
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There have also been sporadic attacks by radicals from the outlawed ultra-leftist Revolutionary People's Liberation Party-Front (DHKP-C).
On any possible security lapses that allowed the Ankara attack to take place, Ala said: "It's our duty that even if there is a one percent weakness to bring it to light."