The three people arrested in Eastleigh on Saturday night had transfer forms, not BVR kits, the Nairobi police commander has said.
Japheth Koome said on Sunday that the papers were for the transfer of people to other centres.
"They had 33 papers. They are in my custody at Pangani police station," Koome told the Star on Sunday.
"I have the papers. Once guided by the IEBC on whether an offence has been committed, they will go to court."
The commander assured that the National Police Service was committed to a free and fair election on August 8.
"Anybody committing any offence will go to court. We cannot take chances. I have called the IEBC because they are the experts. If an offence was committed they will pay for it," he said.
The commission said on Sunday that it had been following up on the alleged registration of voters in Eastleigh using kits believed to have been stolen by al Shabaab militants.
"It is illegal for anyone to purport to be registering or transferring voters without authority from the commission," the IEBC tweeted.
Al Shabaab was accused of stealing four BVR kits after attacking Arabia police post in Mandera East. They denied the allegation.
The attackers also made away with three rifles and an AP Land Cruiser.
More on this: Shabaab take off with 4 BVR kits in Mandera
IEBC communications manager Andrew Limo said information in the stolen BVR kits was encrypted and inaccessible to anyone other than commission.