Terms of the deal were not disclosed and the acquisition is subject to regulatory approval.
Hidroprojektas has 175 staff and is based in Kaunas, which is the second largest city on Lithuania. The firms focuses on hydropower, water supply and infrastructure. It is owned by Lithuania-based industrial holding group Invalda.
In a statement, the Swedish consultant said that the acquisition would takes its total staff from 80 to 800 in central and eastern Europe.