SOFIA (Reuters) - Rumen Radev, the candidate of Bulgaria's opposition Socialist party, narrowly won the first round of the presidential election in Bulgaria with 24.8-26.7 percent of the vote, exit polls by Alpha Research and Gallup International showed on Sunday.

Former air force commander Radev, 53, will face ruling GERB's party candidate Tsetska Tsacheva in a run-off for the highly ceremonial post of the vote on Nov. 13. Tsacheva scored 23.5-22.5 percent, exit polls said.

(Reporting by Tsvetelia Tsolova; writing by Radu Marinas)