"The accused have been charged with planning an incendiary attack on a nanotechnology centre under construction," Switzerland's top criminal court said on its website, without giving further details about the suspects.
The attorney general confirmed the nationalities of the suspects, adding that the Swiss national was resident in Italy.
"The accused were allegedly in possession of explosives which they had allegedly transported into Switzerland without authorisation," added the court.
The three individuals were arrested on April 15th 2010 with explosives and other components to build a bomb, and have been held in preventive detention since then, according to the Swiss attorney general's office.
They also carried with them 31 handwritten letters in German, claiming responsibility for a bomb attack on the IBM nanotechnology facility, on behalf of the "ELF Switzerland Earth Liberation Front," added the attorney general.
Meanwhile, about 50 demonstrators surrounded by police demonstrated in front of the courthouse in southern Switzerland's Bellinzona in support of the accused.
The late 2010 bomb attacks on the Swiss embassies in Athens and Rome were also launched in retaliation for their arrest, according to the Swiss Federal Intelligence Service.
The Earth Liberation Front, born in Britain in the 1990s, is made up of numerous autonomous cells around the world.
During congressional testimony in 2004, FBI deputy assistant director John Lewis had said that the group had "emerged as a serious domestic terrorist threat."
The targetted IBM nanotechnology research centre, in the small suburb of Rueschlikon some five miles south of Zurich, focuses on "novel nanoscale structures and devices to advance energy and information technologies," according to its website.
The court is expected to issue a ruling on Friday.