Russian President Vladimir Putin is due in Vienna for talks with Austrian leaders on the South Stream natural-gas pipeline as well as the crisis in Ukraine.
Putin is also expected to meet Swiss Foreign Minister Didier Burkhalter, who is chairman in office of the OSCE, as the group opens its annual security conference in the Austrian capital.
A top Putin aide, Yury Ushakov, said Putin will oversee the signing of a shareholder agreement between Gazprom and energy firm OMV.
Ushakov said Putin will try to win Austrian backing for the pipeline after Bulgaria suspended work on it earlier this month under pressure from the European Union.
The European Commission has called on all 28 member states to resist pressure from the Kremlin over the project, saying the contracts Gazprom has signed breach the bloc's competition rules.
Based on reporting by AFP, Interfax, and ITAR-TASS