Sadyrbaev questioned a decision by the Supreme Court in April 2005 to acquit Kulov of all charges, saying the court ruling was politically motivated, coming as it did shortly after angry crowds forced President Askar Akaev from power in late March 2005.
At the time of Akaev's ouster, Kulov was serving a prison sentence for alleged abuses committed when he occupied a number of public posts in the mid-1990s.
Sadyrbaev claimed "the judges incorrectly acquitted Kulov owing to the revolutionary mood of the time."
"Kulov must now either go back to jail and sit out his term, or, so that history will not judge him harshly, he has to be acquitted properly, according to the law. There is no third way," Sadyrbaev said.
Sadyrbaev also called for an investigation into charges that Kulov ordered listening devices to be placed in the office of Omurbek Tekebaev, a member of parliament.