Bank staff in Venezuela have called a two-day strike, putting further pressure on President Hugo Chavez.

Staff from the Fetrabanca union will walk out on Thursday and Friday, adding more momentum to a six-week national strike.

Banks have already cut their opening hours from six to three hours a day.

The opposition accuses President Chavez of mismanagement and authoritarianism, and is demanding his resignation.

The strike has crippled the oil production on which Venezuela, the country's fifth largest exporter, depends.

Left-wing presidency

Tens of thousands took part in an anti-tax protest on Tuesday, tearing up blank tax returns and promising a fiscal boycott.

The protesters cheerfully shredded tax forms

"This government uses our money to repress people," one of the protestors, Luis Carlos Bustillos, told the Associated Press news agency.

"This will cause chaos for a few months, but it's better than chaos for a lifetime," Mr Bustillos said.

Security forces patrolled the headquarters of the tax agency, but there was no violence. The opposition began the strike on 2 December, to try to force Mr Chavez to either stand down or call a referendum on his rule.

But Mr Chavez says there can be no vote until August.

Tensions heightened on Friday, when two supporters of the president were shot dead during clashes with anti-Chavez protesters in Caracas.

Correspondents say there is no end in sight to the strike, which has severely affected food and fuel supplies.

The president has raised the possibility of declaring a state of exception, which would allow him to suspend some constitutional guarantees.