Beijing’s tightened grip on the rampant abuse of UnionPay International’s card system has yet to see any effect in Macau. In fact, authorities are reporting that the number of unauthorized transactions using cards from the mainland China’s bank has almost doubled in the first half of 2016.

Between January and June, the Judiciary Police (PJ) calculated a total of MOP2.1 billion (USD262.5 million) worth of illegal transactions in the territory, Portuguese news agency Lusa reported. The amount is almost double the MOP1.22 billion (USD153 million) calculated for the full year of 2015.

For the first half of 2016, PJ opened a total of 12 probes into cases involving money transactions using unregistered UnionPay point of sale (POS) terminals. All of the cases were sent to the Public Prosecutions Office for further action, according to the news outlet.

Police have identified 31 people in connection with the investigation—22 of whom were from mainland China. Authorities also seized 22 POS units that they believed have been tampered so that the UnionPay network will identify them as being registered an operated in mainland China, where transactions fees are much lower compared to Macau.