HAIKOU, Jan. 14 -- Offshore duty-free shopping in south China's Hainan Province surged in 2013, with total sales reaching 3.3 billion yuan (540 million U.S. dollars), up 40 percent year on year.

Offshore duty-free stores received more than 1.1 million customers and sold 4.47 million items, up 6 percent and 28 percent year on year respectively, according to statistics released by Haikou Customs on Tuesday.

Hainan has two duty-free shops, with one in the provincial capital of Haikou and the other in the resort city of Sanya.

The island province has seen booming tourism since an offshore duty-free program began in April 2011 on a trial basis.

Tourists and locals aged 16 or above can enjoy duty exemptions on certain imported commodities worth no more than 8,000 yuan before flying to other destinations within China.

China has made efforts to promote Hainan as an international tourist destination by issuing duty-free policies, tax refunds after departure, and visa exemptions for tourists from 26 countries.