The corporation made its statement on Thursday, saying it was working to restore power supply.
"Guri has faced sabotage … It is a part of an electric war against the state. We will not allow this! We are working to restore power supply," the corporation wrote on Twitter on Thursday.
A Sputnik correspondent reported on Thursday that in Caracas, metro lines had been shut down. Moreover, local residents experienced mobile service outage.
Venezuela's Electric Power Minister Luis Motta Dominguez subsequently said the authorities were working to solve the blackout issue.
"We are getting ready to restore power supply as soon as possible… It could take three hours," the minister told the Telesur broadcaster.
Since January, Venezuela has been facing protests against President Nicolas Maduro.
On January 5, lawmaker Juan Guaido was elected the head of the opposition-controlled National Assembly, which all other government branches have been refusing to recognize since 2016.
The United States immediately recognized Guaido, after which some 50 other countries, including Colombia, followed suit. Russia, China, Cuba, Bolivia and a number of other states have, in the meantime, voiced their support for the legitimate government of Maduro. Mexico and Uruguay have refused to recognize Guaido, declaring themselves neutral and promoting crisis settlement via dialogue.