Those now in power led the rebel army that drove out the Hutu killers in 1994.
In Rwanda in 1994, the world watched while the Hutu majority slaughtered some 700, 000 Tutsis.
Under threat from Hutu extremists, they believe they must have military control to survive.
Nkunda says his forces are fighting to defend Congolese Tutsis from Hutu militants who escaped to Congo.
He said the rebel Hutu groups so far excluded from earlier talks would no longer be "ignored".
The strongest support for Mr Mandela's peace plan comes from the predominantly Hutu Burundian Democratic Front (Frodebu).
The purge is led by the prime minister, Pierre Celestin Rwigema, a Hutu who presents himself as a progressive.
Burundian officials say that Rwanda's Hutu militiamen, the interahamwe, were responsible for much of the recent killing around Bujumbura.
Most of the 800, 000 people killed were ethnic Tutsis but Hutu moderates were also slaughtered by the Hutu extremists.
He joined the Hutu rebellion in 1995 and rose through the ranks to become head of the FDD in 2001.
Rwandan Hutus remained in the jungles of eastern Congo, where they preyed on local residents and participated in Hutu militias.
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Nkunda has accused the Congolese government of failing to protect the Tutsi tribe from Rwandan Hutu militia in Congo.
At the time, Nkunda said his forces were fighting to defend Congolese Tutsis from Hutu militants who escaped to Congo.
The Rwandans are the soldiers of the former Hutu government who fled to Zaire, together with genuine refugees, in 1994.
The Hutu militants believe Mr Museveni is the mastermind of a plot to create a Tutsi empire in Central Africa.
Despite its past as a Hutu rebel group, the movement claims to have rapidly recruited Tutsis since becoming a political party.
Although he signed the deal, Gen Nkunda has always refused to disarm while Rwandan Hutu rebels still operate in the area.
Four Hutu deputies have already been thrown out of both their party and the assembly, accused of identifying with old-style extremism.
But the rebel groups still fighting say that while Tutsis dominate the army, a Hutu president would be mere window dressing.
She is also accused of transferring money to the mainly ethnic Hutu FDLR rebels, based in neighbouring Democratic Republic of Congo.
The two Hutu rebel groups, who remain outside the peace process, have been fighting against the minority Tutsi dominated army since 1993.
Nkunda, a Tutsi, has repeatedly blamed the Congolese government for failing to protect the Tutsi tribe from Rwandan Hutu militia in Congo.
Some moderates from the Hutu majority who supported Tutsis were also killed.
With good reason: in a country with an 85% Hutu majority, a Tutsi-led government would be hard pressed to win an election.
If Mr Buyoya stayed on, it would stir many Hutus to shift their support from peaceful Hutu parties to violent rebel groups.
The perpetrators of the genocide a mixture of politicians, priests, and militias fled to Congo where they hid among more than 1m genuine Hutu refugees.
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But 104 out of 617 incidents involved the murder, often on a large scale, of Hutu refugees by Mr Kagame's forces and allies.
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Ethnic Tutsis, who make up 15% of the population, have traditionally dominated Burundi and this has continued since independence, angering the Hutu majority.
Under the power-sharing deal, Tutsi President Pierre Buyoya is due to swap places with his Hutu Vice-President Domitien Ndayizeye on 1 May 2003.
He was defence minister from 2000 until November last year, when Rwandan spokesman Joseph Bideri said he was sacked for his "extreme pro-Hutu" views.
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