In this undated photo, Bilibili's logo is shown on a smartphone screen. (PHOTO / VCG)

BEIJING - China's internet watchdog has directed popular online entertainment platform Bilibili to rectify issues including the illegal use of foreign audio and video materials, illegal advertising, and disseminating pornographic and vulgar content.

Since the beginning of this year, the office has received over 500 related complaints from the public concerning Bilibili, according to the statement

The rectification aims to strengthen the supervision of the website, which is very popular among China's youth, to protect minors online, said the National Office for the Fight Against Pornography and Illegal Publications in a statement on Monday.

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Since the beginning of this year, the office has received over 500 related complaints from the public concerning Bilibili, according to the statement.

Authorities in Shanghai, where the website is based, on Dec 3 ordered Bilibili to rectify its issues within two weeks.

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For websites dominated by young users -- like Bilibili -- content security is more important than website hits and should be properly supervised, read the statement, noting that Bilibili has 197 million active monthly users, most of whom are under the age of 25.