A major clean-up operation was launched after the petrol tank ruptured spilling fuel onto the road.
Dyfed–Powys Police said: “At approximately 06:40 this morning an RTC involving a fuel tanker and a crane occurred. No injuries have been reported.
“As a result a substantial amount of fuel has leaked from the ruptured tanker.
“Specialist equipment is being used to remove the fuel spillage and the road is going to be closed for a protracted period of time, up to 24 hours.”
It is believed the incident involved a Texaco tanker and a Grove mobile crane owned by Davies Crane Hire.