"I can confirm that 11 players were arrested for match-fixing," a spokeswoman for the interior ministry said. "All of them are Bulgarians."
She said that the initial investigation was triggered two months ago by signals of illegal betting but refused to reveal more details.
Local media reported that Chernomorets's Rumen Trifonov and his team mate Preslav Yordanov were taken in handcuffs from the police station in Burgas and driven to an undisclosed destination.
Interior Minister Tsvetan Tsvetanov said that four of the footballers would probably be charged.
"Our coach Dimitar Dimitrov told me that a few players had been arrested," Chernomorets owner Mitko Sabev said. "We're sure that they didn't manipulate Chernomorets games."
Neftochimik coach Dimcho Nenov said he was not aware that any players had been questioned and confirmed that all players took part in Thursday's training session.
Chernomorets are sixth in the Bulgarian league with 27 points from 15 games. Neftochimik are top in the second division with 28 points from 13 matches.
Media reports of widespread match-fixing and corruption have been rife in the Balkan county for years but no one has been brought to trial and the European Commission has criticised the authorities for doing little to fight the problem.
In September, Bulgaria's prosecutor opened an investigation into claims of match-fixing in four domestic games this season.
The first documented manipulated game in Bulgaria took place in 1949, when Levski Sofia and city neighbours Akademik drew 1-1 in order that CSKA, Levski's bitter rivals, would be relegated to the second division. (Reporting by Angel Krasimirov; Editing by John Mehaffey)