In a major policy reversal, the popular messaging app Telegram has announced it will give users' IP addresses and phone numbers to authorities in response to valid legal requests in an attempt to rein in criminal activity on the platform.

"We've made it clear that the IP addresses and phone numbers of those who violate our rules can be disclosed to relevant authorities in response to valid legal requests," Telegram CEO Pavel Durov said in a post.

To that end, the company now explicitly states -

"If Telegram receives a valid order from the relevant judicial authorities that confirms you're a suspect in a case involving criminal activities that violate the Telegram Terms of Service, we will perform a legal analysis of the request and may disclose your IP address and phone number to the relevant authorities."

Such data disclosures, it said, will be included in its periodic transparency reports. It further noted that the service may collect metadata such as IP address, devices and Telegram apps used, and the history of username changes to tackle spam, abuse, and other violations.

It's worth noting that a previous version of its policy applied only to terror suspects: "If Telegram receives a court order that confirms you're a terror suspect, we may disclose your IP address and phone number to the relevant authorities."

The update to Telegram's Terms of Service and Privacy Policy is a major volte-face for the company which has refused to police the platform for years, turning it into a major haven for cybercrime and other illegal activities, including drug trafficking, child pornography, and money laundering.

The changes have also been driven by the arrest of Durov in France over allegations that the company turned a blind eye to various crimes flourishing unchecked on the platform. He was subsequently released on bail but has been ordered to stay in the country pending ongoing investigation.

Last week, the Ukrainian government said it was banning the use of Telegram by government officials, military personnel, and other defense and critical infrastructure workers, citing national security concerns.