BEIJING - Chinese telecom service has been required to verify and register users' ID when selling new phone cards from Sept 1, the nation's telecommunications regulator said on Friday.

The mandate is the latest effort to better enforce a regulation passed in 2013 that required identity verification when accessing telecom services, including fixed phones, cell phones, and the Internet.

Due to lax implementation of the policy, there remains a large number of unverified accounts, including old clients who bought sim cards before 2013.

Currently, users can obtain sim cards without ID in non-official channels, such as newspaper stands and phone stores ignoring the rule.

All three companies' brick-and-mortar shops are required to have ID card readers to verify and register new users' information starting next month, the Ministry of Industry and Information Technology said on Friday. So far 600,000 card readers have been installed.

Meanwhile, old and unverified accounts that were activated before the 2013 policy will also be verified when users are applying for new service packages or changing phone cards.

In China, unverified cards, known as "black cards", are widely used in fraudulent activities such as text message scams.

China Mobile, China Telecom and China Unicom, the nation's three major operators, all have unverified accounts. China Mobile, the top operator, said in January it still had nearly 130 million accounts, or 16 percent of its total accounts, unverified.

By pushing forward the regulation, the ministry required the three companies to lift the ratio of verified accounts to 90 percent of the total by the end of this year.