China’s leading search engine Baidu has halted—sans any warning—all bitcoin and digital currency-related advertising on its network.

Chinese media outlet CnLedger broke the news on Friday, with a tweet that said Baidu “has stopped all virtual coin related keyword advertising (paid search), including bitcoin.” Local bitcoin exchanges OKCoin and Huobi has confirmed the ban to Bloomberg News, but declined to comment on it.

The way analysts see it, there are two possible reasons why Baidu has decided to quietly remove digital currency promotions. First, the decision could be part of the company’s plan to cull out Ponzi schemes or scam-like cryptocurrency advertisements on the platform. Or it could be due to a request from the government.

Zennon Kapron, managing director of Shanghai-based consulting firm Kapronasia, told Bloomberg the move “could be a precursor to China being ready to push for a more nationalized approach to virtual currencies.”