UC Browser has over 500 million downloads, and is a popular alternative to Chrome in India.

Alibaba-owned UC Browser is no longer available for download from the Play Store. The app is particularly popular in India, where it briefly overtook Chrome to become the most-used mobile web browser in the country earlier this year. The browser has a userbase of 420 million globally — racking up 500 million downloads on the Play Store last month — with over 100 million coming from India.

There's no statement as to why the app was taken down, but the prevailing theory on Reddit is that the malicious redirect ads served up by UC Web's affiliates to inflate installs prompted Google to take action and delist the browser.

An email received by Android Police founder Artem Russakovskii from UC Union (UC Web's affiliate network) reinforces this theory:

Dear Partner, We hereby emphasis again that UC Union prohibits any and all misleading/malicious advertising method(s) to procure new users when promoting UC Browser campaigns, such as by using slogan inconsistent with the Product functions, or by using inductive slogan.

DO NOT use the Malicious Promotion method(s) or STOP such behavior immediately if you are acting so.

Upon discovery a Malicious Promotion, UC Union is entitled to

(i) STOP your payment settlement, or DEDUCT your corresponding payment made to you;

(ii) compensation in recovery of the loss suffered by UC Union, including but not limited to loss of UC Union's good will, loss of users of UC Union Product(s), removal of UC Union Product(s) from Google Play or Apple Store, and any other loss as a result of your Malicious Promotion;

(iii) require you to CLARIFY the facts for elimination of the negative impact shed upon UC Union; and (iv) resort to any other legal measures if necessary.

UC Union is looking forward to cooperating and developing with you in a healthy UC Union ecosphere.

The browser gained momentum in India over the last few years for its speed and sheer number of features, which included a robust download manager, customizable add-ons, and integration with third-party services.

While India is the second-largest market for UC Browser, an article in the Times of India back in August suggested the Indian government was looking to ban the browser for sending user information back to China. Today's delisting doesn't seem to be related to the security vulnerabilities reported in that article, however.

Although UC Browser isn't available for download, UC Browser Mini is still up on the Play Store.

Update: It looks like the ban is temporary, and UC Browser should be making its return to the Play Store in just over a week.