“The people are afraid of you, bloggers are afraid of you, artists are afraid of you, governors are afraid of you. And you are the president of our country,” said the blogger.
Investigators have questioned two men, one of whom confirmed the storage of the ammonium nitrate, the authorities said.
At least 30 people were killed by the explosion in the republic of Dagestan in the Caucasus, according to local officials.
Several draft offices had been attacked since Russian President Vladimir Putin declared a partial mobilisation on Wednesday.
