Swiss Post has announced plans to cut 2,500 jobs and drastically reduce the number of its mail processing centres.
The proposed restructuring measures - deemed necessary to compete in a liberalised market - could affect 3,500 workers or six per cent of the workforce.
Under the new plan the country's 18 mail sorting centres are to be closed and replaced by just three units.
Announcing the cuts on Tuesday, the Post Office said the measures were necessary if it was to compete in a liberalised market. It expects to save SFr200 million ($133 million) per year.
"We are aware that our plans will not be met with enthusiasm by the affected personnel, towns and cantons," said Ulrich Gygi, CEO of the Post Office.
Around 1,000 employees of the Post Office have taken to the streets throughout Switzerland to express their anger at the announcement.
If the board of directors gives the green light to the project - dubbed "Reengineering Mail Processing" - the new measures will be introduced in 2006.
The Post Office argues that even though its existing mail sorting centres are near railway stations, they are strategically in bad locations because they are difficult to access by road.
In a statement, the trade unions said the cuts were part of a "catastrophic project" which had not been analysed in depth. They claim it could actually affect as many as 8,500 postal workers.
The unions also say that most of the workers affected by the job cuts would be women, who work part time and are dependent on their income.
The unions further argued that the project had to be analysed, double-checked and adjusted, as the consequences of such drastic measures would be disastrous in certain areas.
"It can't be right that a few narrow-minded technocrats are allowed to ruin 8,500 lives for financial reasons," the statement said.
However, the Federal Office for Communications welcomed the plan, arguing that it would guarantee the survival of a high-quality service.
The Office said there would be enough time to introduce other measures to reduce the number of proposed job cuts, and to ensure adequate provisions for affected workers.
Gygi said the Post Office wants to remain the number one post carrier in ten years, despite difficult market conditions.
swissinfo with agencies
The Post Office plans to cut 2,500 jobs and to close the country's 18 mail sorting centres.
The cuts would save SFr200 million annually.
The trade unions claim as many as 8,500 postal workers could be affected by the new measures.