By Edmund Blair
NAIROBI, Dec 13 (Reuters) - Rwanda's supreme court extended the jail term of an opposition politician on Friday to 15 years from eight after she sought to overturn her initial conviction for trying to undermine the state and minimising the 1994 genocide.
Rights groups have described the conduct of Victoire Ingabire's trial as flawed. Human Rights Watch said some of the charges were politically motivated and the trial raised questions about the independence of the judiciary.
Rwanda has routinely dismissed such criticism.
"I can confirm that the sentence has been increased to 15 years," Iain Edwards, one of Ingabire's lawyers, told Reuters by phone.
Ingabire, who was jailed last year, returned to Rwanda in January 2010 from exile in the Netherlands to contest a presidential election that year but was barred from standing after being accused of crimes linked to genocide denial.
President Paul Kagame, who won the 2010 vote in a landslide, has secured international praise for rebuilding Rwanda after the mass killings. But critics accuse him of being authoritarian and trampling on media and political freedoms, charges he rejects.
"This is the supreme court. As far as appeals, in Rwanda are concerned that is the end of the line," Edwards said.
He said there was a possibility of taking the case to the Tanzania-based African Court on Human and Peoples' Rights but this would depend on a further study of the ruling.
Ingabire, head of the unregistered FDU-Inkingi party, was imprisoned for eight years last year for conspiring to form an armed group to undermine the government and for seeking to minimise the genocide.
Edwards said both those convictions were upheld, while she was also found guilty on Friday of spreading false rumours intended to incite the public to rise up against the state. She had originally been acquitted of that charge.
Ingabire, who denied the charges, had appealed on several grounds, alleging unfairness in the trial procedure and misapplication of the law. The prosecution, meanwhile, had sought a tougher sentence and further convictions.
"Even going back to the trial in the High Court last year, there were several factors on which we reached a conclusion that she did not get a fair trial," said Carina Tertsakian, a senior researcher on Rwanda for Human Rights Watch.
"Some of these charges are politically motivated because they relate to statements she had made as an opposition politician criticising the government," Tertsakian said, saying there was "a lack of independence of the Rwandan justice system in political cases of this kind".
More than 800,000 people were killed in Rwanda when an ethnic Hutu-led government and ethnic militias went on a 100-day massacre in April 1994, murdering Tutsis and moderate Hutus. (Editing by Andrew Roche)