Paul Kagame told The Associated Press during a stop in London on his way to New York for the UN General Assembly meeting: "There are no grounds whatsoever to say these people ... should be given any amnesty."
He said he did not oppose amnesty in all cases, noting that other genocide suspects had been forgiven as part of his country's justice and reconciliation efforts. But he said the groups who fled to Congo included masterminds of the genocide who had shown no remorse, so they must be either brought to justice or militarily defeated.
In 1994, more than 500,000 people, mainly Tutsis and moderate Hutus, were slaughtered in Rwanda's 100-day genocide.
Rwanda has invaded Congo twice since 1996 with the stated aim of hunting down the Hutu extremists who fled there. Rwanda's second invasion, in 1998, took Africa into a war that involved the armies of six nations, split Congo, and caused the deaths of an estimated 3.2 million people in Rwanda-controlled east Congo, primarily through famine and disease.
Kagame also offered advice to Congo's next president, expected to emerge from an October 29 run-off. He said the run-off's loser should be invited into the government to ensure peace after years of war in the country.
Both Congolese run-off candidates lead personal armed groups that clashed after no one won a majority in the first round, underscoring the possibility that Congo could plunge back into widespread violence and chaos.
Rwandan Hutu extremists have been accused of fomenting instability in eastern Congo for years. They remain entrenched in eastern Congo despite a UN-led campaign to quell the threat they pose.
Kagame, who led the Tutsi rebels who ended the genocide in Rwanda in 1994, said he would work with the new Congolese government against the Hutu extremists, but he said he could not envision offering them amnesty, as the Congolese have done for some of their own rebel groups as a strategy to ensure peace.
Kagame said that Rwandans had succeeded in rebuilding their nation because they took responsibility for the violence and for devising processes for coping with its aftermath.
He has also said that international justice for genocide suspects is flawed, and in the interview said he believed the Rwandan legal system was ready to take over from the UN's International Criminal Tribunal for Rwanda.
"People have to own up and take responsibility, work hard, and not wait for anybody to come and deal with these problems.
"Because they never come, in any case."