The Venezuelan president, Nicolas Maduro, has threatened the seizure of factories that have stopped production and the jailing of their owners.

In a speech to supporters in the capital Caracas, he said the country had to recover the means of production, to counter its deep economic crisis.

On Friday, he introduced a new, nationwide state of emergency.

Opposition protesters have been rallying in Caracas to push for a recall vote to eject him from power.

Maduro said the state of emergency was needed to combat foreign aggression, which he blamed for Venezuela's problems.

And he said military exercises would take place next weekend to counter "foreign threats".

Venezuela has the world's largest oil reserves but its economy has been severely hit by falling global oil prices. Its economy contracted by 5.7% last year and its official inflation rate is estimated to be topping 180%.

There are severe shortages of food, medicines and basic goods which Maduro argues are due to business leaders and the US waging an economic war against his government.

'ALL MEASURES'

The threat to seize closed factories came after Venezuela's largest food and beverage company, the Polar Group, halted production of beer, blaming government mismanagement for stopping it importing barley.

The group's billionaire owner, Lorenzo Mendoza, is a fierce critic of President Maduro.

"We must take all measures to recover productive capacity, which is being paralysed by the bourgeoisie," Maduro told a rally in Caracas.

"Anyone who wants to halt [production] to sabotage the country should get out, and those who do must be handcuffed and sent to the PGV [Venezuelan General Penitentiary]," he said.

An opposition protester shows a mock empty refrigerator to protest against shortages. Photo: AP

"We're going to tell imperialism and the international right that the people are present, with their farm instruments in one hand and a gun in the other... to defend this sacred land," he added.

On Friday he declared a full-blown state of emergency, expanding the state of "economic emergency" he had announced in January.

In an address to the nation, he said the measures would be in place for three months but would likely be extended over 2017.

He did not specify if there would be limits to other constitutional rights but he said the decree would provide "a fuller, more comprehensive protection for our people."

A previous state of emergency was implemented in states near the Colombian border last year.

It suspended constitutional guarantees in those areas but did not suspend guarantees related to human rights.

The Venezuelan Minister for Communication and Information, Luis Jose Marcano, said the state of emergency would allow the government more resources to distribute food, basic goods and medicines.

But he added that it also created "mechanisms for the security forces to be able to guarantee public order needed because of the threats by armed groups".

'TIME BOMB'

The opposition has collected and submitted a petition with 1.8 million signatures in favour of a referendum on Maduro, but the National Electoral Board (CNE) has so far not verified them.

The verification process was supposed to take five days but 12 days have already elapsed.

Opposition activists say authorities are not letting them proceed to the next stage when they must collect another four million signatures.

Addressing the crowds on Saturday, opposition leader and former presidential candidate Henrique Capriles said: "We want a country without queues, where we can find medicines. We want change."

He described Venezuela as a "time bomb that can explode at any given moment".

According to the Venezuelan Constitution, if a referendum is held before the end of the year, a recall vote against Maduro would trigger new elections.

Opposition protester Marisol Dos Santos said there would be "a social explosion" if Maduro did not let the recall referendum happen.