Chavez threatens state of emergency

Opposition protests continued for a sixth day on Saturday.

In a speech to supporters in Caracas, Mr Chavez accused his opponents of trying to sabotage the oil industry, which provides half the government's revenue.

The vice-president of the state oil company, Jorge Kamkoff, told the BBC that production was down 40%, with key refineries about to shut down.

Strike leaders have stepped up their calls for Mr Chavez to resign after gunmen killed three opposition supporters at a demonstration on Friday.

Military role

President Chavez announced that oil tanker captains and senior staff of the state-owned oil company PDVSA who have joined the strike are being replaced.

Defence Minister Jose Luis Prieto has said that Venezuela's armed forced would protect the oil industry.

On Friday, naval boats surrounded the Pilin Leon tanker and its cargo of 280,000 barrels of oil after its crew dropped anchor in Lake Maracaibo and joined the strike in what Mr Chavez called "an act of piracy".

Another boat was taken over on Saturday.

Thousands of people have marched through the Venezuelan capital, Caracas - some supporting and some opposing the government of President Hugo Chavez.

The marches come one day after three people were killed and 29 injured when shots were fired at an opposition rally.

Oil hit

Crude oil production has dropped by up to a sixth of the total national output since refinery workers and oil tanker crews joined other strikers, threatening the economic backbone of the world's fifth biggest oil exporter.

Analysts have warned that a shutdown for longer than two days could have a major impact on US and world oil prices.

Mr Chavez said on Saturday that the strike had severely curbed oil-production but not started to affect petroleum exports.

"International clients have not been affected. There have been delays in production and this could affect exports if it is the intention of the strike to sabotage the PDVSA," he said, referring to the state-run oil company.

"I am more concerned by internal than external supply," he added.

Support of poor

The opposition are increasingly calling for the president to resign, and not as before to agree to a referendum on early elections, our correspondent says.

The president's supporters, mostly made up of Venezuelan's marginalised and poor, were out in force as well, defiantly chanting that now and always Chavez will be president.

"I had to come to show my rejection of the way the opposition is always blaming innocent people for the violence," said Peggly Martinez, a 19-year-old university student. "There's no dictatorship here and we want the world to know it."