The two vehicles collided at 5.45am on the stretch of the A470 between the Pontybat Crossroads and Felinfach.
Stagecoach Wales, who operate the TrawsCymru T4 service between Brecon and Newtown and the T14 service between Brecon and Hereford, tweeted to warn commuters at 7.23am.
The tweet said: “Due to an accident at Pontybat Road in Brecon. All T4 and T14 services are stuck, as police have closed the road for at least two hours.
“Update to follow when the road is open. Sorry for any inconvenience caused.”
The road re-opened at 7.30am once the vehicles had been recovered.
Dyfed-Powys Police said that there were no injuries following the pre-rush hour incident.
A force spokeswoman said: “Police attended a two vehicle collision on the Brecon to Felinfach stretch of the A470 at 5.45am this morning – Thursday, November 28.
“A lorry and car were involved. There were no injuries.
“The road was blocked until the vehicles were recovered. The road re-opened at around 7.30am.”