Tough measures to cool the property market in China’s resort island of Hainan have put the brakes on a real estate boom and underscore the policy risks developers and investors face as the government tries to rein in prices.

Home prices in Hainan, known for its resort-lined beaches, recorded China’s second-fastest monthly price increase in April, spurred by Beijing’s commitment to promote the island province as a tourism hub and free trade zone.

But new measures in April restricting non-residents from buying homes on the island, where non-locals normally comprise about 80% of purchases, have caused sales to plunge.

Home transactions in Hainan in terms of area fell 14 percent in May compared with April, and were down 41 percent from a year ago, according to the real estate research firm CRIC.

The slide comes as the State Council maps out plans to transform Hainan into China’s largest free trade zone and upgrade its core industries to include not only tourism, but also modern services and high technology.