Usually, the bridge allows around 80 trucks to pass each day, but only 20-30 are able to do so now.

China was tightening screening procedures for vehicles carrying goods as a coronavirus prevention measure, slowing down exports, said a department representative who did not want to be named.

As a result, over 200 trucks carrying agricultural produce and seafood are now unable to pass through the floating bridge.

Among the stuck vehicles are 37 carrying dragon fruits, 29 on the Vietnamese side. All of them have refrigeration, so the quality of dragon fruits would not be affected, the department rep said.

Cross-border trade between Vietnam's Mong Cai Town and China's Dongxing City via a floating bridge on the Ka Long River was happening normally, except for Vietnamese dragon fruit, the department said.

"China said it would suspend import of dragon fruits from September 15 to September 21 after detecting the novel coronavirus on some product packaging," said a department representative who did not want to be named.

Drivers in the waiting area have been quarantined. All drivers and other personnel at the border have also had their samples collected for Covid-19 testing, and all the results have returned negative so far.

On Thursday, the Ministry of Industry and Trade said China had announced it would suspend trade at the border for a week, from September 15 to September 21, as it had detected the presence of the novel coronavirus on the packaging and carton boxes containing dragon fruits imported from Vietnam.

Dragon fruit trade should resume after 11 p.m. September 21, but if further tests reveal the presence of the coronavirus on any product, such products would also see their trade suspended for a week, Dongxing City authorities have announced. If an agricultural product tests positive thrice, its trade would be suspended for four weeks, the city added.

China, which is Vietnam’s second largest export market behind the U.S., has been tightening imports of Vietnamese produce in recent months as the country endures its fourth Covid-19 wave.

It temporarily suspended produce imports on several occasions in July and August, greatly affecting Vietnamese exporters.