The authorities in Saudi Arabia have stepped up warnings to women not to defy a ban on female drivers by taking part in a mass driving protest.
The interior ministry has reiterated that anyone flouting the ban is likely to face unspecified punishment.
Saturday's planned protest is the third of its kind since 1990.
About 17,000 people signed a petition calling either for women to be allowed to drive or for an explanation of why the prohibition should remain in force.
Campaigners are encouraging women to take to the wheel in defiance of the ban.
After the 1990 protest, a number of women were arrested or lost their jobs.
An interior ministry spokesman, Mansour al-Turki, considerably toughened the Saudi government line on the women drivers' campaign on Thursday.
A previous statement on Wednesday was confusing, with both those pro- and anti- the campaign believing it favoured them.
'Mood changing'
But Mr Turki explicitly restated that women were prohibited from driving, with violators - and their supporters - likely to face unspecified measures.
A campaign activist, Zaki Safar, said that this was an unusually explicit statement of the ban, which is informal rather than enshrined in Saudi law.
"It is no longer an issue of a social choice - that the government does not itself support the ban," Mr Safar told the BBC.
"No, the spokesman was very clear. And any woman who drives on the 26th will face punishment."
Some Saudi women who took part in the 1990 protest were arrested
But Mr Safar believes the government is still sending mixed messages, as it is itself 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.
As part of the latest campaign, dozens of women have posted online videos of themselves driving in different Saudi cities. None of them has been arrested.
The activists behind the campaign believe the public mood is changing, with many more people - including an increasing number of men - publicly supporting the lifting of the ban.
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