LONDON, march 11 (Reuters) -- Rwandan foreign minister Louise Mushikiwabo said on Wednesday the thawing of her country's relations with France may have paved the way for last week's arrest of a leading Rwandan genocide suspect in Paris.

French judges had sped up their investigation into Agathe Habyarimana since the diplomatic rapprochement in November, Mushikiwabo said on a visit to celebrate Rwanda joining the Commonwealth.

The widow of former Rwandan President Juvenal Habyarimana, who died in a plane crash in 1994, is suspected of having instigated the genocide in Rwanda in which 800,000 ethnic Tutsis and moderate Hutus died in less than 100 days.

"I don't know if it's a coincidence that she's been apprehended but we've had four French judges come to Rwanda to look for evidence since November after years of delay," she told a news conference at the Rwandan High Commission in London.

Habyarimana was briefly arrested on an international warrant issued late last year by Rwandan authorities, who have called on Paris to pursue genocide suspects living in France. She has been forbidden from leaving French territory.

Rwanda has made no official extradition request for the 68-year-old who fled to France in 1994. A French judicial source said it was unlikely she would be returned to Rwanda for trial.

Her lawyer, Philippe Meilhac, rejected the accusations against his client as baseless. But Mushikiwabo said the Rwandan people were convinced of Habyarimana's guilt.

"From the mid 1980s she was a woman who was central in the genocide enterprise. Every single Rwandan in the country at the time will tell you stories about her," she said.

Mushikiwabo praised French President Nicolas Sarkozy for helping restore diplomatic ties between the two countries.

"When he came to power President Sarkozy reached out and said 'I want to have direct dialogue with Rwanda', and he showed a lot of good will. We responded to his personal involvement and request for trust," she said.

Mushikiwabo said she was hopeful Rwanda's high commissioner to India would be extradited by South Africa to face questioning on his alleged links to recent grenade attacks in Kigali.

Lieutenant-General Faustin Kayumba Nyamwasa, a former army chief of staff, fled to South Africa last month after being questioned by police about the attack, which killed two people and injured 30.

"We are hopeful we will get good help from South Africa. We know for a fact that Mr Nyamwasa has links with another defector and he's part of a network trying to spark instability," she said.

Mushikiwabo told reporters Rwanda was no nearer to returning captured rebel general Laurent Nkunda to authorities in the Democratic Republic of Congo, citing concerns over the possibility of his being sentenced to death.

Nkunda was arrested in Rwanda in January 2009 and DRC officials want him returned to face war crimes charges.