Rwandan prosecutors said Tuesday that a prominent critic of President Paul Kagame had been charged with inciting insurrection against the state as well as other offences.
Provisional detention was requested for Diane Rwigara, who was blocked from challenging Kagame in August's presidential election, as well as for her mother Adeline Rwigara and her sister Anne Rwigara.
"The charges include forgery of documents and signature counterfeiting by Diane, sectarian practices by Adeline Rwigara and inciting insurrection for all the three," a spokesman for the state prosecutor's office, Faustin Nkusi, told AFP.
Diane Rwigara has said they were questioned by police almost daily in the first three weeks of last month, before being detained for questioning on September 22.
There was no mention of allegations of tax evasion, which had been raised previously.
In an interview with AFP just before her detention last month, Rwigara 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.
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 accident in 2015, which she has claimed was an "assassination".