Bunge says Argentine gov't demanded up-front taxes

* Tax agency accuses Bunge of multimillion-dollar evasion

* Bunge denies charges, links raids to payment demand

BUENOS AIRES Oct 5 (Reuters) - Grains exporter Bunge, which had its premises in Argentina raided in a tax probe last week, said on Tuesday officials had warned companies last month they would have "serious problems" if they did not make an up-front income tax payment.

The raids were carried out on Friday as the South American country's courts investigate accusations by the AFIP tax agency that Bunge (BG.N) evaded as much as $298 million in income tax from 2007 to 2009. [ID:nN01107902]

Bunge, which denies the charges, said senior government officials had demanded grains exporters pay an extraordinary, up-front income tax payment during a meeting on Sept. 20.

"(They warned) that failure to pay would mean serious problems for the companies and their boards of directors," a company statement said.

"We can't help but link this serious incident with the raid that was carried out and the charges that have been formulated," it added in unusually strong public criticism of the government.

A source at the tax agency, who spoke on condition of anonymity, told reporters on Monday documents gathered in last week's raids proved that evasion had taken place.

Argentina is the world's No. 3 soybean exporter and the top supplier of oil and meal, but the government of President Cristina Fernandez has a tense relationship with the agricultural sector.

Late last month, the head of the AFIP agency accused four of the country's largest grain exporters of tax evasion during last year.

Soy is Argentina's No. 1 export earner and Rosario grains exchange sees this year's agricultural exports totaling $24 billion due to a bumper soy and corn harvest. (Reporting by Helen Popper; Editing by Gary Hill) (helen.popper@thomsonreuters.com; +54 11 4318 0655; Reuters Messaging: helen.popper.reuters.com@reuters.net))