Argentina gov't seen altering biodiesel export tax

* Gov't raised export tax, cut local price in August

* Measure drew complaints from small-scale producers

* Industry sources expect sliding-scale tax announcement

By Maximiliano Rizzi

BUENOS AIRES, Sept 18 (Reuters) - Argentina is expected to unveil a sliding-scale tax system for its multibillion-dollar biodiesel exports following complaints from producers over a tax hike announced last month, industry sources said on Tuesday.

In August, center-left President Cristina Fernandez raised levies on biodiesel shipments and cut domestic prices in an effort to boost local supplies, but small-scale producers said the move would put many plants out of business.

Argentina is the world's biggest supplier of biodiesel, which local producers make almost entirely from soybean oil.

"Tomorrow (Wednesday) they have called industry leaders to the Presidential Palace at 6 p.m. (2100 GMT) and the president will announce measures related to biodiesel," a member of an industry group told Reuters, asking not to be named.

"My understanding is that the measure has been coordinated with the private sector," another industry source said, confirming a report in daily La Nacion that said the sliding-scale system would have a minimum rate of 17 percent.

August's export tax hike, which sought to boost supplies to the home market to help reduce costly fuel imports, raised the levy on exports of the plant-based fuel to 32 percent from about 20 percent.

La Nacion said the variable rate would be adjusted every 15 days, but did not say what the upper limit would be.

A government spokesman could not immediately be reached to comment on the report, which also said a new domestic price was set to be announced on Wednesday.

Fernandez's government cut the official domestic price of the fuel to 4,405 pesos ($942) per tonne last month from the previous month's value of 5,196 pesos per tonne.

Local energy companies are required to sell diesel containing 7 percent biodiesel.

Four years ago, the government's attempt to introduce a sliding-scale tax system on exports of soy products, soybeans, corn and wheat triggered months of angry protests by farmers that eventually forced Fernandez to scrap the measure.

Argentine biodiesel production in 2011 was 2.4 million tonnes, of which 1.7 million was exported for about $2.1 billion. The country plans to reach 4.5 million tonnes of annual production by 2013.