GENEVA (AFP) - Swiss voters headed to the ballot box on Sunday for a referendum on axing the draft, with the Alpine country expected to buck a European trend against conscription given the army's role in the national image.

Opinion polls ahead of the plebiscite showed around two-thirds of voters likely to reject the proposal to scrap conscription spearheaded by pacifists and backed by left-wing parties.

Switzerland's political right, parliament and cross-party government all oppose the plan, and not simply due to cliches about the army being as Swiss as its pocket knives.

Countries across Europe have ditched the draft in the two decades since the end of the Cold War, and pro-change campaigners say Switzerland should follow their lead.

But supporters of the status quo argue that other nations which axed conscription have struggled to fill their ranks since the military became just another career option, putting defence at risk.

Switzerland has not been attacked since the early 1800s, though the two world wars sparked mass mobilisation.

Armed neutrality has been the bedrock of its defence policy for two centuries, with part-time soldiers keeping their arms at home, and also playing a major role in disaster relief or security at international summits.

Switzerland is ringed by friendly nations, but the pro-draft camp says a mass, part-time army is essential in a world of morphing threats - something the referendum campaigners reject hands down.

"Here in the middle of Europe, it's not going to be in the next 15 or 20 years that we'll be able to take the prospect of an invasion of Switzerland seriously," said Tobias Schnebli of the anti-military group GSoA.

"Compulsory military service is a tool created for wars of the past," he told AFP.

Male Swiss citizens aged between 18 and 32 start with a seven-week boot camp and take six 19-day refresher exercises over ensuing years. Since 1992, non-military service, for example in environmental projects, has been available for conscientious objectors.

Supporters say the army is part and parcel of the country's "militia" system - a label the Swiss use not only for the army but also to their part-time politicians and others involved in public service, such as volunteer firefighters.

"Abolishing military service would break the genuine link uniting the people and the army," insisted Defence Minister Ueli Maurer.

They also argue that the draft helps cement a country with three main language groups - German, French and Italian - and where federal power is limited.

On top of that, they point to the army's role as a social and professional leveller, saying it helps bring the Swiss together in ways that are missing in more class-divided societies.

Critics reject those arguments, underlining that only men have to serve, that almost half of those called up do not serve after being rejected on health or other grounds, and that middle class urban dwellers are more able to avoid donning a uniform.

Men who do not serve pay a special tax of four percent of their salary instead.

A string of military reforms for budgetary and strategic reasons have repeatedly reduced the army's pool of troops from 625,000 in 1961 to today's 155,000.

By 2016, the figure is set to be 100,000 - a leaner and fitter force, supporters say.

But critics say that is still colossal in a nation of eight million.

Neighbouring Germany, for example has 10 times the population and 183,000 active troops.