Russian dock workers at St Petersburg and Tuapse ports owned by billionaire Vladimir Lisin may strike next month if wages are not increased, a union official said.

“A strike is possible,” local united trade union spokesman Vasiliy Denisenko said. “The dock workers have launched the procedure for a collective labor dispute.”

He added that consumer prices rose 8.5 percent in St. Petersburg last year, while wages rose 5 percent.

He did not say how many workers could possibly take part in the industrial action, which would be the first at the two ports since 2007.

St Petersburg is a key port for thermal coal exports to the UK, Germany and Scandinavia. The Black Sea port of Tuapse handles coal shipments to Turkey. (Reuters)