It's a response to calls for further scrutiny by skeptics who say backers couldn't possibly have legitimately collected signatures from more than half of the country's 9 million eligible voters in just 16 days, and say three days wasn't sufficient time to properly vet them.
The text of an election commission resolution was printed in the state-run media today. It says that only the commission protocol confirming the validity of all those signatures will be preserved.
The resolution reads: "All the [petition] papers with the signatures have the status of confidential information and should be kept at the [Central Election Commission] for three months and then should be destroyed in accordance with this resolution."
The document goes on to detail the manner in which the signatures will be disposed of. It states they will be destroyed "via burning, melting, tearing into pieces not bigger than 2.5 square centimeters, shredding, chemical solution, or turning all the papers into formless mass or powder."
Signed, sealed, and obliterated.
The resolution is dated January 13, the day when a self-styled "initiative group" submitted its petition drive to the election commission.
The commission later announced that 5,016,000 signatures were verified as valid and some 194,000 signatures invalid.
The constitutional amendments have passed through parliament and Nazarbaev has sent them to the Constitutional Council for a decision on whether they are constitutional.
Nazarbaev -- who last year was declared by parliament to be the "leader of the nation" -- said earlier this month that he does not support the efforts to extend his term until 2020. But Nazarbaev said on January 20 that if a decision is made to hold the referendum he will "do his best to take into consideration the interests of the nation and the state."
-- RFE/RL's Kazakh Service