A general view of Haitang Bay duty-free shopping center in Sanya, South China's Hainan province. [Photo/Xinhua]

HAIKOU - Since the offshore duty-free sales began in 2011 in China's island province of Hainan, the total sales have exceeded 13.4 billion yuan ($2.2 billion).

Haikou customs on Tuesday said that offshore duty-free stores had received around 4.7 million customers and sold more than 17.4 million items over the past four years.

Hainan has two duty-free shops, with one in the provincial capital of Haikou and the other, the world's largest such shop, in the resort city of Sanya.

The State Council, China's cabinet, gave Hainan permission to run a trial duty-free program in April 2011 in an effort to make the island a world-class tourist destination by 2020.

Non-locals can make duty-free purchases twice a year when leaving the island, each capped at 8,000 yuan.

The island province has seen booming tourism since the program started. It is expected to receive 47 million tourists this year.