Kallas said that Russia could be about to cut off the three Baltic countries from the electricity grid.
Plans to test the connection between Russia's main power network and the Kaliningrad exclave were delayed on Saturday. The testing is seen as a way for Russia to get rid of the Baltic nations from the grid.
Kallas said in an interview with the public broadcaster that they have been preparing for desynchronization for a long time, but if Russia does this suddenly, we may have power cuts.
After the start of the war between Russia and Ukraine, the Baltic nations stopped buying electricity from Russia. Russia is still the main supplier of electricity to the region.
The Baltic nations have been trying to get rid of their dependence on Russian energy for a long time. The region could be connected with continental Europe's power system in a matter of hours, but a sudden disconnection could lead to days of power cuts.
The longest separation test has been conducted by Kaliningrad, lasting 72 hours.