Mexico’s central bank said on Tuesday it had raised the security alert level in its payment system after a non-banking financial user reported “inconsistencies” in the cash payment matching system.

Insurer Axa said in a separate statement it suffered a cyber attack on Monday that prompted the central bank alert, but that its clients’ information and resources were safe and had not been affected.

Some institutions would be operating via an alternative mechanism until further notice as a precautionary measure, the central bank said in a statement, without providing details.

In May, the central bank said a cyber attack had tapped into payment system connections at five entities, removing around 300 million pesos ($15.3 million).