He stated this during a meeting with leaders of factions of the State Duma.
Putin said that the nationwide vote on constitutional amendments will be modeled on the presidential election law.
“This means that the responsibility for violations of the procedure should be the same as for similar violations during the voting in the presidential election,” TASS quoted him as saying.
He added that he instructed to make appropriate changes to the administrative and criminal codes.
The president also called on parliamentary parties to send observers to polling stations. He noted that "everyone is interested in the fact that the vote was held in accordance with the highest standards, ensuring the purity of the procedure, and results that would not raise doubts."
Putin also said that constitutional amendments are in demand.
On February 27, the State Duma committee approved the amendment to vote on the Constitution on April 22.