Seoul: South Korean technology giant Samsung Electronics has been given the green light by Vietnamese Prime Minister Nguyen Tan Dung to build a $300 million research and development centre in the capital Hanoi, the media reported on Friday. Once operational in 2019, the 21-storey facility will cover three hectares, employ about 6,000 people and develop high-tech electronic and telecommunication products, the company said. It will also operate rent-free for 50 years, EFE news reported. Vietnam has become one of Samsung's biggest production hubs, and the firm has invested almost $15 billion in two production facilities in the country's north, and in Saigon. Producing Samsung products has helped Vietnam replace clothing and footwear with smartphone and electronics manufacturing as the country's largest source of export revenue. Smartphone exports alone were worth $30 billion last year, making up 18.6 percent of the Communist country's total export revenue.