Neher said prosecutors were investigating the cause and extent of Taboga's debt.
Kuljic was arrested in a parking lot in Anif near Salzburg on Tuesday while waiting for Taboga, expecting the Groedig defender to hand over 3,000 euros ($4,020). Taboga had warned the police the evening before.
The deputy chief of the Salzburg state office of criminal investigation, Karl-Heinz Pracher, said Taboga had given money to Kuljic several times before, "sometimes by post, sometimes in person."
"The threats were done by mobile phone through calls and text messages," Pracher said.
A man accompanying Kuljic on Tuesday was also arrested but released shortly afterward. According to Neher, the man had driven Kuljic from Vienna to Anif but was not a suspect.
Kuljic, born to Bosnia-Herzegovinian parents in 1977, played for nine Austrian clubs including Austria Vienna, and was with Ried when he became the top goalscorer in 2005-06. He also had stints at Sion and Neuchatel in Switzerland and Larisa in Greece. He retired in 2012 after tearing ligaments.
Kuljic scored three goals in 20 games for the national team but was overlooked by then coach Josef Hickersberger for the 2008 European Championship co-hosted by Austria and Switzerland.