On Wednesday the federal council tasked the justice department to draft a bill on the issue, following a year of consultation, it said in a statement.

The new law would require companies with 50 or fewer employees to examine the salaries they pay staff once every four years and report the results.

An external body or auditor would ensure companies were complying with the law, and that their directors were aware of the results.

“It’s been 35 years since salary equality between men and women was inscribed in the Constitution, but it hasn’t yet been achieved,” the government said in a statement.

Voluntary measures haven’t worked, it said, hence this attempt to force the issue via legislation.

The government had suggested that the results of the quadrennial salary checks should be shared with employees of the company, which would offer transparency and push businesses to correct any salary inequalities.

However that proposal had been abandoned after the majority of those consulted objected to the move, said the government.

In September ten cantons signed up to a new charter agreeing to salary checks in public sector organizations.

However as yet there is no such agreement in the private sector

Despite equality being enshrined in Swiss law, women on average earn between 15 and 20 percent less than their male colleagues.

A 2015 Eurostat survey put the Swiss gender pay gap at 19.3 percent, three percent greater than the European average.