Swiss voters on Sunday gave their national intelligence service greater powers to spy on terrorist suspects and cyber criminals.
In Switzerland, where privacy is considered an important right, the intelligence service currently has to rely on information from public sources and from other authorities.
Some 65.5 per cent of the 5 million Swiss voters approved the bill in the wake of recent terrorist attacks in Europe, according to the final results.
The bill, due to go into force on September 1 next year, would allow agents to tap phones and computer networks under certain conditions.
Left-wing political groups have warned that the law would violate citizens' privacy, and that it would undermine Switzerland's neutrality as the secret service would also be allowed to cooperate with foreign agencies.
Citizens cast their ballots on two additional referenda on Sunday.
They rejected a Green Party plan for a sustainable economic model to be established by 2050, with 63.6 per cent voting against. They also rejected a proposal to raise government pensions by 10 per cent, with 59.4 per cent against.