A Rwandan court on Monday refused to grant bail to Diane Rwigara, a prominent critic of President Paul Kagame who has been charged with inciting insurrection against the state as well as other offences.
Rwigara was blocked from challenging Kagame in August's presidential election and arrested on September 22, along with her mother and sister, for alleged tax evasion and forgery as well as for inciting insurrection.
Her mother Adeline was also refused bail on similar charges by the court in the capital Kigali, but charges against his sister Diane were lifted and she was released from custody.
In an interview just before her detention last month, Rwigara, 35, said she was a victim of political persecution "for standing against oppression and speaking my mind."
Other critics and opposition figures have also been detained in recent weeks in what observers say is a post-election crackdown on dissent.
The refusal to allow her to run against Kagame, who won the August 4 election with 99 percent of the vote, on claims of procedural irregularities was widely criticised by Western governments and rights groups.
The court on Monday spoke of the "sensitivity" of the case, adding that Rwigara and her mother could flee the country if they were released.
Insurrection carries a possible 15-year prison term.
Rwigara is the daughter of Assinapol Rwigara, an entrepreneur who made a fortune in industry and real estate, and a main backer of Kagame's Rwandan Patriotic Front (FPR) during its efforts to topple the Hutu extremist regime in 1994, ending the Rwandan genocide.
Diane Rwigara later distanced herself from the FPR after her father's death in a car crash in 2015, which she has claimed was an "assassination".