"We have received pre-prepared forms to be used by paid-up observers, lists of violations that have been written up beforehand that just need the number of the polling station and a signature," Onalsyn Zhumabekov, head of the Central Election Commission, said.
President Nursultan Nazarbayev, in power since 1989, is widely expected to win Sunday's vote in the vast oil-producing Central Asian state but his main opponent Zharmakhan Tuyakbai has already accused officials of seeking to rig the vote.
Zhumabekov accused the opposition of wanting the election to be declared fraudulent so that it could organise street protests, which are illegal in the ex-Soviet state without the express permission of the authorities.
"I suggest these and other facts are convincing proof that the opposition ... is planning to hold illegal protests using the pretext of artificially selected violations of the election law"
head of Central Election Commission
"I suggest these and other facts are convincing proof that the opposition ... is planning to hold illegal protests using the pretext of artificially selected violations of the election law," he told reporters late on Thursday.
Tuyakbai has said the opposition will not break Kazakhstan's laws, including those outlawing spontaneous protests.
About 1,100 election monitors are observing Sunday's vote, including 460 from the Organisation for Security and Cooperation in Europe (OSCE), widely seen as the most objective.
"They are not here for money"
OSCE election monitoring spokeswoman
OSCE election monitoring spokeswoman Urdur Gunnarsdottir said she was not aware of Zhumabekov's remarks and said OSCE monitors, who are all volunteers and many of whom are diplomats, could not be bribed.
"It would be a futile exercise," she said. "They cannot easily be bribed, they are foreigners and they have absolutely no reason to take money. They are not here for money."