Late Thursday, security authorities announced they had intercepted a van carrying up to 500 kilograms of explosives on the road to Ankara. The van, which was registered in Germany, had crossed into Turkey via the Kapikule border gate with Bulgaria.
Bulgarian customs officials had tipped off Turkish security that the van appeared to be suspicious, and it was later stopped before it reached its destination.
Reports say that four persons, including two Turkish nationals, were detained by security forces. It is believed that the van had travelled from Sweden.
On Tuesday, a 300 kilogram bomb was found inside a minibus parked in a multi storey car park in the centre of Ankara. The bomb was defused by police before it could be detonated.
To date, no arrests have been made but police have said they are seeking a male with an Arab accent.