Supermarket shelves are starting to empty in parts of Argentina as a national strike by farmers continues into its third week.

The strike was triggered earlier this month when the government in Buenos Aires introduced a new system of export taxes on commodities such as wheat, beef and soya.

For example, soybean taxes were increased from 35% to 45%, as the government attempted to boost its revenue in the wake of booming global commodity prices.

But the move has angered farmers, who have set up road blocks and refused to supply grain terminals and cattle markets for over two weeks.

Mercado de Liniers (the country’s main cattle mart) had no cattle on offer yesterday or today,” said a spokesman for exporters Argentine Beef Packers. “The beef plants managed to get small numbers of cattle through the blockade, but they are all short of livestock for the home market and have killed nothing for export this week.

“Whilst the dairy farmers have opted out of the strike, the roadblocks are the main cause of concern in moving livestock. There is still no sign of talks between the government and the farmers to settle the dispute.”

Grain exports have been similarly disrupted, and now the impact of the strike is being felt among the country’s retailers, with shops emptying of beef, chicken, milk, pasta and vegetable oil, according to media reports.

The strike is being seen as a major test for Argentina’s president Cristina Fernandez, who this week pledged not to give in to extortion. She indicated a willingness to negotiate with farmers, but only once they had ended their strike.

But farm leaders have pledged to continue their action indefinitely, accusing the government of profiteering off the backs of farmers.