The popular initiative ‘For an orderly withdrawal from the nuclear energy programme', backed by the Green Party, will be put to the public vote in a referendum on November 27th.
If passed, three of Switzerland's nuclear power reactors – Mühleberg and Beznau 1 and 2 – will be closed as soon as 2017, with the remaining two being decommissioned in 2024 and 2029.
Supporters say Switzerland's ageing reactors – Beznau 1 is the oldest in the world, in service since 1969 – pose a threat to the country and the older they get the more risk there is of a major nuclear accident.
The popular initiative sets a timetable for their closure, says the Green Party, which argues that Switzerland is well positioned to make the transition to clean energy.
The country is already 56 percent fuelled by hydroelectric energy, which is Switzerland's most important domestic source of renewable energy, according to the Swiss energy office.
Some 40-45 percent of Swiss electricity comes from nuclear power.
The Federal Council already has plans to pull the plug on nuclear power by 2050 in its ‘energy strategy 2050' set in motion after the Fukushima nuclear power disaster in Japan in 2011.
But the timetable set out by the popular initiative was not realistic, it said on Tuesday.
“Getting out of nuclear power makes sense, but we need more time,” energy minister Doris Leuthard said at a press conference on Tuesday.
In a statement on the subject, the government said: “The reduction in electricity output could not be compensated quickly enough by electricity generated from renewable sources.
“This would mean that Switzerland would have to import a large amount of electricity in the coming years.
“This would undermine the security of supply and would not make ecological sense, because foreign electricity is often produced by coal-fired power stations.”
Former Green Party MP Christian Van Singer, who sits on the initiative committee, disagreed, saying it was possible to buy clean energy from abroad that costs less than Swiss nuclear energy, reported news agencies.
But premature decommissioning would also lead to compensation claims from their operators, said the government.
“The Federal Council is committed to a gradual withdrawal from the nuclear energy programme, thereby giving Switzerland sufficient time to restructure its energy supply system.”
Last week the Swiss People's Party (SVP) said it planned to challenge the government's ‘energy strategy 2050', saying it was irresponsible to move away from nuclear power.