Brazil on Wednesday temporarily halted the paving of an Amazon road while it demarcates 13 nearby conservation areas to discourage illegal logging.

Environment minister Carlos Minc said the government will not assign construction contracts for at least two months for BR-319, a muddy, 500-mile (an 800-kilometer) track that will be transformed into a two-lane highway between the jungle cities of Manaus and Porto Velho.

Paved roads in the Amazon allow soy farmers and ranchers to get their goods to market much more cheaply. Brazil is the world's top beef exporter and the No. 2 soy exporter behind the United States.

But critics say improving Amazon roads without adequate environmental planning beforehand promotes illegal logging to clear land for agribusiness and spurs waves of migration — causing uncontrolled development in pristine jungle areas.