The landslide happened when a hill of construction waste collapsed, leaving 74 people either missing or dead.
The formal arrests come three days after the police took what Chinese media called "coercive measures" against 12 people. It is thought the 11 arrested today were among those.
Officials have described the 20 December disaster as man-made, raising the possibility of severe punishments for those they consider responsible.
One official, whose job involved regulating construction sites, apparently jumped to his death a week after the landslide. It is not clear if he was being investigated for his role in it.
Officials have appealed for police and the public to help them find other suspects apparently on the run.
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