Police have arrested two men and a woman suspected of planning to bomb a research facility belonging to the IBM computing firm near Zurich, according to media reports in Switzerland.

Prosecutors confirmed on Monday that two Italians and a Swiss were held on suspicion of planning an attack against an international company, but they would not confirm the target.

They said the arrests occured on April 15 near Rueschlikon, about 10km south of Zurich.

The SonntagsBlick newspaper reported that the suspects intended to attack a nanotechnology research facility that IBM is building in Rueschlikon.

Police discovered "explosive and further items in their car" as well as a note "indicating a planned attack on the branch of an international company," Jeannette Balmer, a spokeswoman for the federal prosecutors office, said.

All of those arrested remain in detention, she said.

"IBM has been notified by Swiss police authorities about an investigation and is co-operating accordingly," Chris Sciacca, an IBM spokesman, said.

He declined to answer further questions, citing the police investigation.