Twitter confirmed the ban in an email to Reuters after Kaspersky Lab co-founder Eugene Kaspersky disclosed the development in a blog post on Friday, saying that the company learned of the ban in early January.

The ban follows charges by Washington that Kaspersky Lab has close ties to intelligence agencies in Moscow and its software could be used to enable Russian spying, which prompted the Trump administration to ban its products from U.S. government networks.

Kaspersky Lab has repeatedly denied those allegations, saying it will open up its code for inspection so that experts can hunt for vulnerabilities in its products that could be exploited by intelligence agencies, and it has asked a U.S. federal court to overturn the American ban.

 The logo of Russia's Kaspersky Lab is on displayat the company's office in Moscow, Russia October 27, 2017. REUTERS/Maxim Shemetov

Eugene Kaspersky said in his blog post that he was surprised by Twitter’s ban and asked the company to reconsider.

“We haven’t violated any written – or unwritten – rules, and our business model is quite simply the same template business model that’s used throughout the whole cybersecurity industry: We provide users with products and services, and they pay us for them,” he said.

Department of Homeland Security cyber-security official Jeanette Manfra said her agency has not instructed U.S. companies to punish Kaspersky.

“We laid out a very transparent process and how we came to our decision,” to ban Kaspersky products from government networks, she said at a panel at the RSA security conference in San Francisco. “I would defer to the companies for how they made their decisions.”

Kaspersky said in an email that Twitter was the only social media company to ban its ads.

But other social media companies have taken action regarding Kaspersky Lab.

People holding mobile phones are silhouetted against a backdrop projected with the Twitter logo in this illustration picture taken September 27, 2013. REUTERS/Kacper Pempel/Illustration/File Photo
 

Facebook Inc in January said it had removed Kaspersky Lab from a list of anti-virus offerings to users.

When asked to explain its ban, Twitter said in an email, “This decision is based on our determination that Kaspersky Lab operates using a business model that inherently conflicts with acceptable Twitter Ads business practices.”

Twitter also said it was responding to a Department of Homeland Security warning of a threat to national security posed by Russian government access to Kaspersky products.

It is rare for Twitter to ban specific advertisers. In October it banned Russian media outlets Russia Today and Sputnik, accusing them of interfering in the 2016 U.S. elections. Last month, Twitter banned cryptocurrency ads.