Lavrov and Deshchytsia are "due to attend a working dinner later, but this is not a bilateral meeting, there will be other foreign ministers there," Austrian foreign ministry spokesman Gerald Fleischmann said.
The last time Lavrov and Deshchytsia, whose Western-backed Kiev government Moscow refuses to recognise, are thought to have met officially was when a deal aimed at resolving the crisis was struck in Geneva on April 17.
Around 30 foreign ministers from the 47-state Council of Europe were expected to attend tomorrow's gathering including Britain's William Hague. Steinmeier and French Foreign Minister Laurent Fabius will however not be present.
The Council of Europe meeting is due to discuss the status of democracy and human rights and cooperation within the European Union before a working lunch on the situation on Ukraine, according to the rights body.
