Turkish security forces have foiled 18 suicide attacks since the start of the year, three of them by intercepting vehicles planned for use as car bombs, Interior Minister Efkan Ala said in an interview with the Kanal 7 television station on Sunday.
Ala said that one of the three vehicles had been found this week at Istanbul's Bogazici University, parts of which were evacuated on Thursday in an apparent bomb scare.
A car packed with explosives was detonated in Ankara this month next to military buses waiting at traffic lights in the administrative heart of the capital, killing 29 people, most of them soldiers.
Nato member Turkey faces multiple security threats.
It is part of a US-led coalition fighting Islamic State in neighbouring Syria and Iraq, and is battling Kurdish militants in its south-east, where a 2-1/2 year cease-fire collapsed last July triggering the worst violence since the 1990s.
The government blamed the Ankara bombing on a member of a Syrian Kurdish militia working with PKK militants inside Turkey. A suicide bomber killed 10 German tourists in the historic heart of Istanbul in January in an attack Turkey blamed on Islamic State.