But provincial governors deny there is a problem with authorities extorting cash from farmers.
Farmers drive loads of palm wood through a village in Kandal province last year.
OPPOSITION Sam Rainsy Party parliamentarian Khim Laky, of Kandal province, has written to Prime Minister Hun Sen requesting that he crack down on illegal provincial border crossings, following renewed complaints from cross-border traders.
The letter, issued Monday, states that illegal checkpoints in Kandal, Kampong Cham, Prey Veng, Takeo and Kampot provinces have forced small-time traders to bribe corrupt border officials to ensure the passage of goods.
"These checkpoints were created to take money from farmers transporting crops," the letter said.
Khim Laky said the illegal checkpoints operate under the guise of transportation tax collection points.
Kandal Governor Chhun Sirun, Kampong Cham Governor Hun Neng and Kampot Governor Khoy Khun Huor told the Post there were no such checkpoints in their provinces.
"I will oust [any] authorities that dare to put [up] illegal checkpoints," Hun Neng said, adding that he had eliminated some checkpoints already.
"If there were illegal checkpoints, the opposition party would be successful in the next election," Khoy Khun Huor told the Post.
Chhun Sirun said that the opposition party was only making this statement to get votes from the poor farmers.
An official of Cheuo Khmao commune in Kandal province who declined to be named told the Post Monday there are two checkpoints in his commune, but he did not know whether they were illegal or not.
Hun Sen has condemned the existence of illegal checkpoints in all provinces, saying that if any province allows corrupt officials to take bribes from struggling farmers, the governor will be ousted from his position.