Facebook on Wednesday said it is loosening its ban on ads related to blockchain and cryptocurrency, allowing more businesses working on those technologies to promote their efforts on the social network.

Facebook first started blocking ads promoting cryptocurrencies and initial coin offerings in January 2018 over concerns that users might be scammed by initial coin offerings offered by some crypto start-ups. The company loosened its ban in June to allow ads from advertisers who received prior written approval. Now, it is further rolling back the policy so that many types of ads will no longer require approval.

"We've listened to feedback and assessed the policy's effectiveness," Facebook said Wednesday in a blog post. "While we will still require people to apply to run ads promoting cryptocurrency, starting today, we will narrow this policy to no longer require pre-approval for ads related to blockchain technology, industry news, education or events related to cryptocurrency."

The company has come under scrutiny over the wide reach of this policy over the past year.

In October, CNBC highlighted the ban's impact on Bloom, a San Francisco start-up that uses blockchain technology to help people keep control over their personal data online. Bloom had spent hundreds of thousands of dollars on Facebook ads to promote its services, but the saw all of its ads suddenly banned by the social network in October.

"It's good to see them (hopefully) evolve their stance on new technology that puts users in control of their data," said Shannon Wu of Bloom in a statement.

Facebook's rollback of this ban comes amid reports that the company is working on its own blockchain project. In December, Bloomberg reported that the company is building a so-called stablecoin that will allow WhatsApp users to send cryptocurrency payments to one another. Facebook has been in talks with dozens of financial firms and e-commerce companies to support the initiative, the Wall Street Journal reported last week.

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