Farmers in Argentina have pledged to continue a nationwide protest after the government refused to back down on tax rises on agricultural exports.

Two weeks of blockades by farmers have left many shops in the main cities short of meat and dairy products.

Amid the shortages, thousands of Argentines, banging pots and pans, took to the streets to back the farmers.

President Cristina Fernandez, in office since December, says the increased taxes on farm exports are justified.

Protesters have been stopping lorries carrying farm produce and either turning them back or dumping their goods on the road.

Speaking on national television, President Fernandez said the agricultural sector was one of the country's most profitable with global demand growing for Argentine beef, corn, wheat and soybeans.

"I'm not going to submit to extortion. I understand the industry's interests but I want them to know that I'm the president for all Argentines," she said, making it clear there would be no talks while the farmers' strike continued.

Soon after her address, demonstrators in Buenos Aires and other cities gathered on the streets to stage pot-banging protests.

"This is a pretty ugly wake-up call for the government after just a few months in power," protesters Hector Bernardino told Reuters.

He said middle-class Argentines, like the farmers, were tired of taxes and double-digit inflation.

Flashpoints

Argentina is one of the world's top exporters of soya, wheat and beef and any prolonged conflict will have a major effect on vital export earnings, says the BBC's Daniel Schweimler in Buenos Aires.

The farmers' strike is the biggest crisis faced by Ms Fernandez since she took office more than three months ago, succeeding her husband Nestor Kirchner, our correspondent adds.

The government has been using taxes on grain and commodity exports to boost state revenues.

Taxes on a range of goods including soybeans, sunflower oil and beef are being raised by up to 45%, increases that farmers have described as crippling.

"We will continue the strike for as long as necessary," said Eduardo Buzzi, president of the Argentine Agrarian Federation (FAA).

Trade at Argentina's largest grain and cattle markets has ground to a halt while many shops are reporting shortages of supplies.

There have been disputes between farmers and truck drivers, and armed police have been deployed at potential flashpoints.