The border has been closed since Sunday to test officials and people on the Chinese side, and it is not known when it would reopen, Lang Son customs officials said.
As of Monday over 1,700 container trucks were stuck at the border in Lang Son Province, including 1,097 carrying fresh agricultural produce.
Huu Nghi accounted for 54 percent of the total number.
Lang Son has said it would stop allowing trucks carrying fresh fruits to the border until March 15, extending a previous deadline by 10 days.
Vietnam earned $1.75 billion from exporting fruits and vegetables to China in the first 11 months of 2021, up 3.6 percent year-on-year despite Covid-19, according to the General Department of Vietnam Customs.