Rwanda's Supreme Court has upheld the conviction of opposition leader Victoire Ingabire and increased her jail term from eight to 15 years.
She was found guilty of threatening state security and "belittling" the 1994 genocide.
The Supreme Court also found her guilty of spreading rumours intended to incite people to revolt - charges on which she had earlier been cleared.
She had appealed against her conviction.
She insists the trial was politically motivated.
The Unified Democratic Forces (UDF) leader, who was in court for the ruling, was arrested in April 2010 months after returning from exile and was barred from standing in elections later that year.
The BBC's Prudent Nsengiyumva in the capital, Kigali, says the court was packed with diplomats and supporters of Ingabire.
After the sentence was read out she shouted out to them that "the fight continues" and urged them not to be discouraged by her jail term, he says.
Both the defence and prosecution had appealed against last year's High Court verdict.
The Supreme Court judge ruled that Ingabire should be serving a 27-year sentence for her crimes, but she had decided to show leniency, giving her 15 years, because her family was based in the Netherlands and that this was her first conviction.
Ingabire, a Hutu, returned from exile in the Netherlands in January 2010 - and has been in jail since her arrest.
She had questioned why Rwanda's official memorial to the 1994 genocide did not include any Hutus.
Most of the 800,000 people killed were ethnic Tutsis but Hutu moderates were also slaughtered by the Hutu extremists.
The prosecution had initially requested a life sentence.
"We are disappointed, of course, but... we are going to wait for the written verdict which will be available as of next week," the AFP news agency quoted her British lawyer Iain Edwards as saying after the hearing.
The UDF's deputy leader, Boniface Twagirimana, said the party was "not surprised" by the verdict.
Ingabire is a leading critic of President Paul Kagame, a former rebel leader whose Tutsi-dominated Rwandan Patriotic Front (RPF) put an end to the genocide, and who has been accused increasingly of ignoring human rights and stamping out any opposition.
He won a second term in office in August 2010 with 93% of the vote and his supporters praise the government for maintaining stability and overseeing rapid economic growth.