Foreign investors have been flocking to the Shanghai Free Trade Zone (FTZ) as reforms in China's economic testbed keep gaining momentum.

The Shanghai FTZ has attracted foreign investment worth $23.5 billion in the first five months this year, Shanghai Municipal Commission of Commerce said on Wednesday.

The money was five times the amount registered in the same period last year, the commission said.

The Shanghai FTZ was launched in September 2013 to test reform policies.

Foreign investors set up businesses in the Shanghai FTZ as reforms have adapted FTZ regulations in trade and finance to international standards, said Shang Yuying, director of Shanghai Municipal Commission of Commerce.

The commission said reform policies in engineering, tourism, and telecommunications have been particularly effective.