Circle Internet Financial is de-emphasizing bitcoin services to focus on global mobile payments, it said Wednesday as it unveiled a new blockchain protocol called Spark and messaging features for its existing app.

The Boston company will continue to transfer money over the bitcoin network, but will focus its resources on global social payments and "future next-generation blockchain technology," instead of supporting the buying and selling of bitcoins directly, its cofounders said in a Wednesday blog post. Users can receive and hold bitcoin in their Circle accounts and it will continue to be insured, but they can no longer buy or sell bitcoin on the app.

Circle, one of the earliest bitcoin exchange and wallet startups to emerge in the space, has also maintained one of the cleanest reputations. Last year it secured a $50 million Series C investment co-led by Goldman Sachs and the Chinese company IDG Capital — at a time when banks' bitcoin worries seemed to calm as they warmed to the promises of its underlying blockchain technology. A few months later it became the first company to receive a BitLicense from the New York State Department of Financial Services.

This year it raised another $60 million from Chinese investors to continues expanding its operations in China, bringing its total funding to date to $136 million.

"Our continued use of bitcoin as a settlement token and network behind the scenes means that Circle will continue to be a leading participant in the digital currency markets and ecosystem, with our focus on getting more digital wallets to adopt public blockchains as open transaction settlement networks," Circle's CEO Jeremy Allaire, and its president, Sean Neville, said in the post.

Instead, Circle is referring customers to bitcoin exchange and wallet provider Coinbase — which counts BBVA, USAA and former Citigroup CEO Vikram Pandit as financial backers — as a preferred partner. Customers can take their bitcoin trading activity to any third party and then use Circle to convert it to dollars, euros or pounds sterling (but the cannot convert it back to bitcoin).

The announcement comes a week after a federal court in California approved a controversial request from the IRS to obtain the records of potentially millions of Coinbase users who had made digital currency transactions between 2013 and 2015, highlighting tension between compliance and customer privacy for financial institutions.

Around the time it received its BitLicense, Circle rebranded its mobile bitcoin wallet app to Circle Pay, which has launched in the U.S., U.K., and parts of Europe allowing users to hold, send, receive and convert U.S. dollars in addition to bitcoin, link credit or debit cards and bank accounts, higher spending limits and FDIC-insured deposits (held at a third-party bank). It also lets people send local currency to other digital wallets over the bitcoin blockchain.

That's the initial focus of its new open source project, Spark: connecting digital wallets globally while ensuring it meets know-your-customer/anti-money-laundering (KYC/AML) and compliance requirements. Spark is a set of additions to the protocol that provides a way for digital wallets to exchange value using blockchains, including the bitcoin blockchain, and settlement layers.

Because Spark is open source, any developer can use and implement the software. Circle said it intends to work closely with similarly minded ecosystem participants to advance the technology and integrate it with additional public and private blockchains.

The first implementation of Spark will be through two new partnerships, one with a Korean company called Korbit and the other with a Philippine company, Coins. Both remittance companies will be able to implement Circle's Spark application programming interfaces to allow U.S., U.K. and European customers to transact with customers in Korea and The Philippines. The experience would have "the speed, security and cost efficiency of distributed ledgers, but with a pure fiat-to-fiat consumer experience" and is compliant with international KYC and AML standards.

Circle Pay also introduced new messaging capabilities. The app is now organized around people instead of transactions, it said. Payments exist in an ongoing conversation between the sender and receiver, a function they likened to the more widely popular messaging WeChat and WhatsApp. In September it integrated with iMessage to allow payments transactions through Apple's text messaging platform.