Saudi authorities have ordered banks to separate female and male workers at their headquarters in a new setback for women's rights in the conservative kingdom.

Banks are one of the main employers of women in Saudi Arabia. Though women are already separated from male employees in branches, they have up to now worked together in bank headquarters.

Under the new system, women employees in bank headquarters could now be obliged to work on separate floors and use different lifts, entrances and canteens from men.

"We are gutted. The flow of business will be ridiculous and we will not be able to attend important meetings, which will significantly hamper our career development," a senior Saudi woman banker said on condition of anonymity.

"We graduated to work in banks because they offered unparalleled career development opportunity in the kingdom, and now this. We are making one step forward and ten steps backwards," she added.

Saudi Arabia's strict Islamic law and customs stop unrelated men and women from mixing, banning them from driving cars and voting in municipal elections.

Some senior Saudi officials have expressed support for women joining the labour force in a country where expatriates hold nearly 90 per cent of jobs in the private sector.

But the powerful religious establishment has strongly resisted any changes, Western diplomats say.

There are up to 3,000 Saudi women among an estimated 60,000 employees in Saudi banks.

Managers from three Saudi banks said the Saudi Arabian Monetary Agency (SAMA) – the country's central bank-and Labour Ministry officials held a meeting earlier this month with bank managers to inform them of the new system. "They want to end the mixing of genders at banks' headquarters. They have initially given us one month to comply but later extended the deadline to the end of the summer holidays," said one of the managers on condition of anonymity.