Thick black smoke rose from the underpass in central Burgas minutes ago, a reporter saw.

A rag soaked in diesel fell from one of the service trucks in the underpass and caught fire, sending smoke into the air.

The smoke drifted towards the Law Courts and was clearly visible to people nearby. Because of the layout of the underpass, the fire looked more serious than it was.

Passers-by were surprised and asked where the smoke was coming from.

The underpass had been closed to traffic for several hours before the smoke appeared. Specialised trucks are working there to clear the drains and drainage system of built-up dirt that stops rainwater from flowing away.

The smoke appeared in a section where crews were already at work. The underpass is a transport link in central Burgas.

Traffic is expected to reopen once the drainage work is finished and the section is made safe.