Venezuela's opposition called on Monday for a national strike against President Nicolas Maduro in an escalation of protests after a massive symbolic referendum at the weekend.

"Hour zero is starting," opposition leader Freddy Guevara said on behalf of the Democratic Unity coalition, using army jargon for a decisive operation and accusing the leftist government of failing to heed the will of Venezuelans.

"We call on the whole country this Thursday to join massively and peacefully a national civic strike of 24 hours as a mechanism of pressure and preparation for the definitive escalation which will be next week," he added.