Cameroonian truck drivers supplying the capital cities of neighboring Chad and Central African Republic said they plan to strike next week in protest at illicit road checkpoints and harassment by police and customs officials.

There are considerably more checkpoints along the two corridors to Chad and Central African Republic than the seven official barriers that have been jointly agreed to, Ibrahima Yaya, president of the Cameroon National Union of Professional Drivers, said by phone on Thursday.

“They don’t let us through if we refuse to pay a bribe,” he said. The truck drivers plan to strike from February 18.

Landlocked Chad relies on Cameroon’s port of Douala for about 90 percent of its imports, including cement and machinery, according to data from the Cameroon Customs Department. An average of 900 trucks per week ply the 1,850-kilometer (1150-mile) road to the Chadian capital N’Djamena, according to the union.

Central African Republic, which is also landlocked, gets 80 percent of its imports via a 1,500-kilometer corridor linking the port to the capital, Bangui, according to the Central African Road Freight Board.

Officials at the Chadian border systematically demand a tax of 46,000 CFA ($78) in addition to between 5,000 and 10,000 CFA truck drivers are asked to pay at each of the more than 20 illicit control posts along the road, according to Abdourahman Bouba, a trucker who plies the Douala-N’Djamena corridor, in an interview in Douala.

“We can neither confirm nor refute the allegations until we undertake field trips,” El Hadj Oumarou, director of the Cameroon Overland Freight Management Office, said by phone.

Aline Ndoumou, a secretary at the Delegation General for National Security in the capital, Yaounde, said by phone her boss was unavailable for comments.