By Raphael Satter

WASHINGTON Microsoft Corp is expanding its suite of free security tools for customers, the software company said on Wednesday, following criticism that it was charging clients to protect themselves against Microsoft's mistakes.

The move follows a high-level hack that allowed allegedly Chinese spies to steal emails from senior U.S. officials - and complaints from security specialists and lawmakers against paying for tools

In a blog post published on Wednesday, Microsoft said the advanced features in Microsoft's auditing suite - which it calls Microsoft Purview - would be available to all customers "over the coming months."

Although not enough to prevent hacks on their own, digital auditing tools are critical for helping organizations figure out whether intruders are in their network, how they got in and how to get them out.

Microsoft's previous practice of charging for advanced versions of those tools has come under widespread criticism, especially following the recently disclosed hack at the U.S. State and Commerce Departments. That hack - which Microsoft later acknowledged was down to a breach and coding flaws - was only discovered because one of the victims spotted an anomaly while reviewing their digital logs.

In a statement released alongside Microsoft's blog post, Cybersecurity and Infrastructure Security Agency official Eric Goldstein said that "everyone wins" when security tools are provided free of charge.

Charging for those tools "is a recipe for inadequate visibility into investigating cybersecurity incidents," Goldstein said.

(Reporting by Raphael Satter; Editing by Josie Kao)