CARACAS/SAN CRISTOBAL, Venezuela (AFP, REUTERS) - Venezuelan opposition leader Juan Guaido on Monday (March 11) called for a new mass demonstration as a devastating blackout that has left millions without power entered its fifth day and the US said it is withdrawing its remaining diplomatic personnel from Caracas.

President Nicolas Maduro, meanwhile, called for grassroots groups to hit back against what he called attacks encouraged by the US against the country's electrical grid. "The time has come for active resistance," he said in a speech.

Guaido, in a speech to the National Assembly which he leads, said "tomorrow at three o'clock in the afternoon, all of Venezuela will be on the streets" to protest against Maduro.

Parliament accepted the 35-year-old's request to declare a "state of alarm" to pave the way for the delivery of international aid, 250 tons of which has been stuck for a month at Venezuela's borders with Colombia and Brazil.

Guaido and the opposition-controlled legislature have no means to enforce it, though, as Maduro controls the military and security services, which are currently preventing aid from entering the country.

Guaido, recognized as Venezuela's interim president by more than 50 countries, called on the military and security services to "refrain from preventing or hindering" Tuesday's protests.

Describing the situation as a "catastrophe," he said the blackout - the worst in the Latin American country's history - had claimed dozens of lives since it began last Thursday (March 7).

Power was restored to some areas of the country over the weekend but - with residents and businesses fearing that refrigerated food would spoil - service was patchy and power often lasted just a few hours before dropping out again.

As the situation worsened, US Secretary of State Mike Pompeo announced Washington is withdrawing all its remaining personnel from the US embassy in Caracas. All non-emergency staff were ordered to leave on January 24.

"This decision reflects the deteriorating situation in #Venezuela as well as the conclusion that the presence of US diplomatic staff at the embassy has become a constraint on US policy," Pompeo wrote on Twitter.

'TRAGEDY'

Even the National Assembly's emergency session fell victim to the blackout, as the electricity supply failed an hour into the meeting.

"We cannot turn away from this tragedy our country is going through," said Guaido, who declared himself acting president in January, triggering a power struggle with Maduro in the oil-rich South American country of 30 million.

Businesses and schools remain shuttered on Maduro's orders, as they have been since the blackout began. In any event, the lack of public transport made travel difficult, even in Caracas.

Maduro extended the closure for another 24 hours on Monday due to the blackout, the second time he has done so. In his speech on Monday night, Maduro asked for resistance from groups known as "colectivos" - grassroots social work groups that the opposition argues have also been armed by the government and act as militia.

Critics say such groups were behind the death of seven people on Feb 23 when the opposition tried in vain to bring US-supplied food and medicine across the borders with Colombia and Brazil.

A ball of flame flared across the darkened sky over southeastern Caracas in the early hours of the morning when the Humboldt power station erupted in a massive explosion, increasing the chaos in an area where looting was reported on Sunday.

"I felt like I was in a horror movie," said Carolina Molina, who witnessed the blast from her window. State-owned electricity company Corpoelec declined to comment on the explosion.

The fire that followed the blast was still smoldering by mid-morning. A metal beam holding one of the huge transformers had melted and a wall had been blackened, Agence France-Presse reporters said.

'HOLLYWOODESQUE'

The power crisis may spell trouble for Maduro's support from the military, the Eurasia Group consultancy said.

"The government's inability to resolve the crisis and the resulting impact on oil exports, along with challenging social dynamics, may start to shift the military's calculations about the sustainability of Maduro's regime," it said.

Maduro has ordered that hospitals - where patients were languishing without proper treatment, and where at least 15 people reportedly died due to a lack of kidney dialysis treatment - should be given top priority.

He has blamed the blackout on US "sabotage" in the form of an electromagnetic attack on the country's main hydroelectric complex in Guri, which supplies 80 per cent of Venezuela's electricity.

Guaido dismissed that explanation as "Hollywoodesque."

Oil industry sources said that exports from the primary port of Jose had been halted for lack of power, cutting off the OPEC nation's primary source of revenue.

People have clustered on the streets of Caracas to pick up patchy telephone signals to reach relatives abroad. On Monday, Venezuelans formed lines to fill containers from a sewage pipe.

Critics blamed the government for failing to maintain the power grid, as did the Lima Group, a primarily Latin American bloc.

For ordinary Venezuelans, the blackout has piled misery upon an already agonizing day-to-day struggle to survive in a country in economic freefall.

Venezuela has been in recession for more than four years, has struggled with hyperinflation the International Monetary Fund says will hit a staggering 10 million percent this year, and seen a mass exodus of an estimated 2.7 million migrants since 2015.

"Every day is worse," said Edward Cazano, a 20-year-old who lives with his mother and three brothers in a poor Caracas neighborhood called Pinto Salinas. "We have the worst services in the world: no light, no water, sometimes no gas."

Winston Cabas, the president of an electrical engineers'professional association, told reporters that several of the country's thermoelectric plants were operating at just 20 per cent of capacity, in part due to lack of fuel.

He said the government was rationing electricity, which explained why some parts of Caracas had power and others did not.

The process of restoring service was "complex" and could take between five and six days, he said.

"We once had the best electricity system in the world - the most vigorous, the most robust, the most powerful - and those who now administer the system have destroyed it," he said.