Argentine farmers will launch a seven-day strike starting on Friday (August 28) that will freeze grain and beef sales from one of the world's biggest suppliers of corn, beef and soybeans, farm leaders said.

The strike, aimed at protesting the government's farm policy, revives a long-running dispute that has rattled local financial markets and tested President Cristina Fernandez over the past two years.

Carlos Garetto, leader of the Coninagro farm group, told a news conference that the strike expressed "producers' unrest and the critical situation in the provinces, which is growing and worsening."

Farmers, who blocked highways and halted grains sales for months last year, have criticized a congressional vote last week that extended the president's powers to set grain export taxes, which are at the center of the conflict.

Their bad mood was fueled this week when Fernandez vetoed part of a farming law that exempted growers and ranchers from paying the export levies in drought-hit parts of Buenos Aires province.    

All four of the country's main farming groups agreed to the strike, which is not expected to hit grains exports or the processing industry since crushers normally have enough inventory to ride out a short protest.

Soy prices in Argentina's main grains market of Rosario ended flat on Tuesday at $262 per tonne as producers were willing to accept offers of Monday's price because they wanted to offload soy in anticipation of the strike.

Fernandez has repeatedly rejected calls to reduce the multibillion-dollar export taxes, a key source of state revenue. The taxes are expected to bring in more than $7 billion next year.

Last year's conflict drove up US soy futures and sent local bond prices tumbling. Local food and gasoline supplies were affected by prolonged road blocks, but farmers on Tuesday pledged supermarkets would be supplied during the new strike.

The farm conflict hurt Fernandez's popularity and voters rejected her handling of the crisis in a June mid-term election, dealing her congressional allies a heavy defeat.

Farmers and some opposition politicians want the government to scrap the levies on corn and wheat and cut the 35 per cent rate on soybeans, but the government says they have not said how they would plug the funding gap.

Economy Minister Amado Boudou and Cabinet Chief Anibal Fernandez denied unsourced media reports on Tuesday that the government was mulling raising the soy levy to 45 per cent, official news agency Telam reported. – Reuters