Merchants in the Dominican Republic have shuttered the biggest border market for trade with Haiti amid that country's ban on some goods entering overland.

Haiti has banned 23 products from crossing by land its border with the Dominican Republic, seeking to improve tax collection and ensure better quality control. As of Oct. 1, such things as drinking water, flour and construction materials can arrive only by air or sea.

On Friday, Dominican traders in the market town of Dajabon began a strike to pressure Haiti to scrap its ban. Union leader Freddy Morillo says the work freeze at Dajabon is "indefinite."

The banned goods represent $500 million in annual sales and make up 6 percent of all Dominican exports. The Dominican government has complained to the World Trade Organization.