In March 2000, Kulov was arrested and charged with abuse of power. An initial acquittal was reversed, and in 2001 Kulov was sentenced to seven years in jail. At another trial in 2002, he was sentenced to 10 years in jail, this time for embezzlement.
International right groups, including New York-based Human Rights Watch, insist Kulov is in prison because he intended to challenge incumbent President Akaev in the 2000 elections. The group has called on Kyrgyz authorities to release him.
Described as Kyrgyzstan's only political prisoner, Kulov has remained politically active while in prison. In November 2001, while in prison, Kulov was elected chairman of an opposition movement called the People's Congress of Kyrgyzstan, which unites several political parties, such as Ar-Namys, Ata Meken (Fatherland), and the People's Party. The People's Congress will be participating in parliamentary elections on 27 February and a presidential poll due in late October.
Observers say Kulov's influence enables him to unite the Kyrgyz opposition. The question, they say, is whether he wants to.
Recently, the People's Congress of Kyrgyzstan held negotiations with another opposition movement called the People's Movement of Kyrgyzstan. The two groups discussed possible unification ahead of the elections.
Kulov spoke about the negotiations from prison in an interview with RFE/RL: "We had preliminary negotiations with the People's Movement of Kyrgyzstan, which was recently established by former Prime Minister Kurmanbek Bakiev. We said we support unification. But there must be certain tactics. At this stage, only those with similar political positions must be united."
Last week, several other Kyrgyz opposition groups announced a plan to work together. Leaders from the People's Movement of Kyrgyzstan, the social movement Ata-Jurt (Fatherland), Jany Bagyt (New Direction), and the For Fair Elections movement signed a memorandum, pledging to work together to ensure that February's parliamentary elections are free and fair.
The leader of the People's Movement of Kyrgyzstan, former Prime Minister Bakiev, explained the group's intentions: "These five movements that had five different directions before have been united. [We united], first of all, in order to prevent any fraud during the parliamentary elections. If there were any illegal activities, then we would jointly fight them."
The People's Congress of Kyrgyzstan is among the signatories of the new grouping. Kulov told RFE/RL that his bloc is ready to join any effort aimed at ensuring elections are open and fair.
But he said it is too early to unite with Bakiev's bloc on other issues, since the People's Movement does not yet have a clear political program: "In order to avoid accusations that we support only a person [Bakiev] but not a policy, a platform, we decided to wait until their political and economic program is announced. Then we can discuss unification."
Observers said Bakiev's popularity and influence might be one reason for Kulov's reluctance to collaborate.
Bakiev, who has been able to unite communists and so-called radical liberals under his centrist group, has announced his intention to run for president and has already received the backing of some opposition parties.
International pressure has led to reports that Kulov might be released from prison ahead of schedule. But even if he is freed before October, Kulov's prison record means he is constitutionally prohibited from running for president.
Muratbek Imanaliev is a former Kyrgyz foreign minister and a leader of Jany-Bagyt. He told RFE/RL that Kulov might throw his support behind another candidate.
"Feliks Kulov is one of the most influential and prominent politicians in Kyrgyzstan, despite his current state -- that is, limited," Imanaliev said. "During parliamentary and presidential elections, he can run political groups under his leadership through existing political mechanisms. It's difficult to say if he would personally choose and support one candidate, but I assume that if Mr. Kulov would decide to do so, his support would play a significant role."
But Imanaliev said Kulov will likely have to wield his influence from behind bars.
"For the authorities, Feliks Kulov is a serious political threat. Therefore, I don't believe the government will release him before the presidential election," Imanaliev said.
(RFE/RL's Kyrgyz Service contributed to this report.)