A fake VAT invoice scam in Shanghai, worth 4.4 billion yuan ($718 million), was uncovered after an investigation, police said at a news conference on Wednesday.

More than 20 suspects, led by two men surnamed Fan and Lou, set up more than 70 shell companies by registering or purchasing readymade corporations that were no longer conducting business.

They submitted more than 100,000 false value added tax invoices for nearly 6,000 enterprises in 28 provinces and municipalities on the Chinese mainland.

The scam, set up in 2011, charged around 8 percent of the amount listed on the invoices.

With the help of police in neighboring Zhejiang province, Shanghai police seized suspects in Shanghai and Zhejiang on July 16 and more than 1,000 related bank accounts were frozen.