Maduro said earlier his government had new proof that the national power grid had been infected by a virus and pointed the finger at the two South American nations, who back self-styled interim president Juan Guaido.
"The Ministry of Foreign Affairs, on behalf of the Colombian government, emphatically rejects the recent statements … accusing Colombia of being a source of ‘cyberattacks’ against Venezuela's electrical grid", the Colombian ministry said in a statement.
Chilean Foreign Minister Roberto Ampuero likewise denied Maduro’s claims.
Most of the country went dark in early March. Sporadic outages continued into April, prompting water shortages. Maduro announced a 30-day plan last week to ration electricity. He has repeatedly accused the United States and its allies of being behind the blackout.
Venezuela has been gripped by unrest since Maduro was sworn in as president for a second term in January. This prompted US-backed opposition leader Juan Guaido to proclaim himself interim president and promise a snap election. He was recognized by Washington and its allies in the region and in Europe.
Constitutionally elected Maduro has accused the United States of trying to orchestrate a coup. Russia, China, Cuba, Bolivia, Turkey and a number of other countries have voiced their support for Maduro as the only legitimate president of Venezuela.