Argentina's government this week will authorize the export of an additional 400,000 tonnes of 2013-14 wheat, two sources in the agricultural sector told Reuters on Wednesday, on top of the 1.5 million tonnes already authorized.

Argentina is one of the world's biggest wheat exporters, but farmers have been planting less of the crop in recent years due to complaints about the government's export quota system that is designed to guarantee cheap and plentiful supplies at home.

"This week they will authorize some from the old season and next week some of the new," a source familiar with the situation said. "Some 400,000 (tons) of the old (2013-14) season and 2 million of the new (2014-15) one."