Three Baltic states on Saturday cut ties with Russia's power grid to join the European Union's network, the culmination of a years-long process that gained urgency with Moscow's war in Ukraine.

Estonia, Latvia and Lithuania – all former Soviet republics now in the European Union and Nato – had wanted to block Russia's ability to geopolitically blackmail them via the electricity system.

"We have removed any theoretical possibility of Russia using energy (grid) control as a weapon," Lithuania's Energy Minister Zygimantas Vaiciunas said on Saturday.

EU foreign policy chief Kaja Kallas – Estonia's former prime minister – had on Friday hailed the grid switch as "a victory for freedom and European unity."

Vaiciunas said the Baltic states had completed the disconnection process at 9:09 local time (0709 GMT) on Saturday.

"We have been waiting for this moment for a long time," he told reporters, after speaking with his Estonian and Latvian counterparts.

"The energy system of the Baltic states is finally in our own hands. We are in control," he added of the "historic" moment.

He said the Baltics were now operating in so-called "isolated mode" before they integrate with the European grid on Sunday.

Official celebrations are planned across the Baltics, and authorities were on guard for any potential cyber-attacks linked to the grid switch.

Latvia will physically cut a power line to Russia later on Saturday and European Commission president Ursula von der Leyen is to attend a ceremony with Baltic leaders in Vilnius on Sunday.

The Baltics have long prepared to integrate with the European grid but faced technological and financial issues.

The switch became more urgent after Russia started its war in Ukraine in 2022, spooking the Baltic states into thinking they could be targeted.

They stopped purchasing Russian gas and electricity after the war began, but their power grids remained connected to Russia and Belarus, controlled by Moscow.

This left them dependent on Moscow for a stable electricity flow, which is crucial for factories and facilities requiring a reliable power supply. (AFP)