A state of emergency has been declared in 21 municipalities of Brazil's Amazon as a severe drought has affected some 40,000 families there since early August, local press reported on Monday.

According to the Amazonas state government, transportation of six tons of humanitarian food aid to the affected area began this week, but it has been slow due to low levels of rivers that prevented large vessels from navigating.

"The boats cannot navigate, and then the transportation can only be done by canoe. In some places, people were running out of food," said Anisio Saturnino, representative of one of the municipalities under emergency rule.

Besides the lack of food, many people are suffering intestinal problems caused by poor water quality.

Ane Alencar, geographer and researcher with the Amazon Institute for Environmental Research (IPAM), said the drought affecting the Amazon is an extreme weather event resulting from El Nino, which occurred in late 2009 with its fallout being felt this year.

She said the drought in the state of Amazonas has been more frequent and more intense than before, so there is no enough time for the forests to recover.