Prosecutors were given the green light by Peru's Congress to charge former President Alberto Fujimori with crimes against humanity, a move officials hope will step up pressure on Japan to force the exiled leader to face justice.

In a special session Monday night Congress voted 75 to 0 to lift Fujimori's constitutional immunity, opening the way for prosecutors to file charges of homicide and forced disappearances for two massacres committed by a paramilitary death squad.

Prosecutors have five days to file what will be the most serious charges yet against Fujimori, 63, who fled in November to his parents' native Japan as burgeoning corruption scandals toppled his 10-year government.

Japan announced Fujimori was entitled to citizenship shortly after he arrived and that he could stay. Japanese officials said they won't force Fujimori to return to Peru since Japanese law prohibits the extradition of its citizens to stand trial for crimes committed in other countries.

So far Fujimori faces only charges of abandonment of office and dereliction of duty, which carry a maximum two-year prison sentence, not enough for Japan to even consider an extradition request.

But Peruvian officials hope that charges of "crimes against humanity" -- what they say are politically motivated kidnappings and killings of groups of people -- would circumvent the extradition issue altogether.

According to Peruvian legal experts, Japan would have to try Fujimori for such charges in its own courts or send him to an international tribunal because it has signed international human rights treaties.

But one Japanese lawyer who specializes in international law said it was "extremely questionable" whether Fujimori would be tried in Japan for murders committed in Peru.

Kazuo Ito said such a trial would require evidence that Fujimori had a direct role in specific murders, not just that he was aware of the existence of a death squad and took no steps to dismantle it.

In the vote Monday, Congress approved an investigative committee's report that says Fujimori is responsible for the actions of the so-called Colina group, a shadowy death squad allegedly run by jailed ex-spy chief Vladimiro Montesinos.

Members of the Colina group gunned down 15 people at a fund-raising barbecue at a Lima tenement building in 1991. The group also kidnapped and executed nine students and a professor at La Cantuta University in 1992.

The attacks were believed to be strikes at collaborators of the Shining Path, a Maoist-inspired guerrilla group that ravaged Peru during the 1980s and early 1990s with car bombings, assassinations and sabotage. The violence dropped off sharply after the capture of key rebel leaders in 1992.

Congressman Daniel Estrada, head of the investigative committee, told said evidence collected by his group showed clearly that the death-squad killings were part of the Fujimori government's strategy to battle the guerrillas.

The massacres "could not have occurred without the consent of the highest spheres of power," Estrada said, in presenting his committee's recommendation.

The report cites testimony from Fujimori's former military chiefs, former intelligence agents and a secretly filmed videotape from 1998 in which Montesinos tells two former officials that the Colina massacres "came from" Fujimori.

There was no immediate reaction to Congress' decision on Fujimori's "From Tokyo" website, which he launched in July to defend himself against what he calls "vulgar political persecution."

In a message posted earlier Monday, Fujimori called the homicide charges "preposterous" and said they were part of a conspiracy against him.