Bulgaria has warned its southern neighbors Greece and Turkey they could face floods as heavy rains are expected to swell the Arda and Maritsa rivers flowing into their territories.
The alert came as Greek emergency services were struggling to deal with their worst wildfires in years.
The Ivaylovgrad dam on the Arda in the eastern Rhodope Mountains would probably overflow in the next few days because of expected downpours, Bulgaria's foreign ministry said late on Tuesday.
The Arda flows eastward into Greece and joins the Maritsa river on Greece's border with Turkey.
Sofia said it was expecting massive increases in water volumes in the flood-prone Maritsa near the Bulgarian town of Svilengrad on the Turkish border on Wednesday and Thursday.
Bulgarian authorities have declared states of emergency in several municipalities following heavy rainfall. A man died after being swept away by floodwaters in the Bulgarian town of Teteven on Tuesday.