The Saudi interior ministry has warned women that measures may be taken against them if they take part in a campaign against a ban on female drivers.
A new campaign to give women the right to drive will culminate in Saudi Arabia this weekend. Women are being encouraged to take to the wheel in defiance of the ban.
It is the third protest of its kind; in the first, in 1990, several women were arrested or lost their jobs.
The BBC reports that the interior ministry has clarified the government line on the campaign. A statement earlier this week was confusing, with both those for and against the campaign believing it favoured them.
But now a ministry spokesperson, Mansour al-Turki, has explicitly restated that women are prohibited from driving, and that offenders - and their supporters - are likely to face unspecified measures.
A campaign activist, Zaki Safar, says this is an unusually explicit statement of the ban, which is informal rather than enshrined in Saudi law. But Mr Safar believes the government is still sending mixed messages, as in his view it is still divided over whether to lift the ban.
Earlier this week, about 100 conservative clerics asked for an audience at the royal court in the capital, Riyadh, to denounce the campaign as a conspiracy by women and a threat to the country.
But there have been indications of a less hardline attitude by the authorities than back in 1990, and at the second protest in 2011. For instance, the latest campaign dozens of women have posted online videos of themselves driving in different Saudi cities - but none has been arrested.
The activists behind the campaign believe the public mood is changing, with many more people - including a growing number of men - publicly supporting the lifting of the ban.