Major tea producing countries last month agreed to stick to ISO 3720 as a minimum quality level to prevent oversupply from depressing prices, he said.
The agreement came at the Intergovernmental Group on Tea of the Food and Agriculture Organization of the United Nations meeting in Hangzhou, China.
"Some countries which were not happy with the ISO 3720 quality standard have now come around and all now have agreed, except Vietnam which is not in the IGG," Hettiarachchi told the annual general meeting of the Colombo Tea Traders' Association Friday.
Sri Lanka Tea Board has been insisting that exporters ship only teas that meet the ISO 3720 standard.
Last year some shipments were allowed after lobbying by certain exporters but these were subsequently halted by the Tea Board.
"Sri Lanka needs national legislation to enforce minimum standards. W