Dubbed as “professional post-deleting”, illegal post deletions is shaping up to be a major problem, but because of the records it keeps of cross references of original posts and any subsequent changes it has managed to spot suspicious activity. Because of the allegations, three out of the four have been arrested as well.

“Baidu has fired the four. If we discover such cases, we will severely punish staff. Baidu will close the loopholes by strengthening management to maintain order in our communication platform,” said the Chinese search engine giant said in a statement to The Global Times.

Delving deeper into such activities, the paper also reported that there are different rates for deleting articles from a forum, a blog or a news portal. Companies offer such services, sometimes also called professional long term maintenance service, by charging anywhere from $23.5k to $31.3k a year. One of the companies also claims that they know Baidu insiders that can do the job for them.