Serbian police are to investigate the 2008 privatization of state oil company NIS, now majority-owned by Russia's Gazprom Neft.
The Interior Ministry on August 12 said it had set up a special investigative team to examine "all the facts and circumstances regarding the privatization of NIS."
Gazprom Neft bought a 51 percent stake in NIS for $534 million in 2008, under a Serbian government led by the current opposition Democratic Party.
The deal was signed in Moscow in the presence of the then-presidents of Serbia and Russia, Boris Tadic and Dmitri Medvedev.
Aleksandar Vucic, the current prime minister, has said the deal was not favorable to Serbia and alleged it also envisioned the sale of NIS.
Based on reporting by Reuters and Beta