Members of the Maoist group also cross the isolated border into Brazilian jungle towns to get supplies or to find women, said Mauro Sposito, head of the Brazilian federal police's Amazon drugs squad on Monday.
One of Latin America's most ruthless rebel groups at the height of its struggle, Shining Path has been largely dormant since the capture of its leader Abimael Guzman in 1992.
But in recent months, it has staged new attacks and incursions. The Peruvian government said this month it was forming a battalion of troops to fight them.
Sposito said Brazil was worried the guerrillas were taking advantage of the absence of Peruvian authorities in the areas where Brazil's Amazon jungle borders Peru.
At least 60 armed Shining Path guerrillas operate in the border region, he estimated.
"There is a very serious logging problem," Sposito told Reuters from the Amazon border town of Tabatinga.
Peruvian loggers pay poor Brazilians to cut down precious tropical timbers. The wood is then hauled into Peru where Shining Path taxes the loggers in return for free passage to markets. The fee helps the group finance its activities, Sposito said.
"There is a very serious logging problem"
chief, Amazon drugs squad, Brazil
The guerrillas also tax the drugs trade. Coca is the raw product used to make cocaine and Peru is the world's No. 2 producer.
There are a number of illegal jungle landing strips on the Brazilian side along the Peruvian border.
Further north on Brazil's jungle border with Colombia, Colombia's Revolutionary Armed Forces of Colombia, or FARC, have slipped over into Brazil for supplies and to aid the passage of cocaine from Colombia.
The Brazilian army and police are opening several new posts along the border to combat threats along Brazil's vast Amazon frontiers.