BURAIDAH, Saudi Arabia—Saudi women's plans to defy their nation's harsh restrictions on them driving is reigniting a fundamental conflict between conservatives and moderates on the kingdom's future.

Even in the country's most conservative town, Buraidah, some traditional women will challenge the de facto ban on driving on Saturday. In the northern desert town where few women are seen in public, let alone behind the wheel, protesters say they have the support of families and friends.

"It is because we are very conservative that I am part of this" campaign, one 50-year-old government worker said Wednesday in Buraidah. "It is my belief and my faith that it is my right to drive my own car."

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Saudi activist Manal Al Sharif, who lives in Dubai, flashes the victory sign as she drives her car in the Gulf Emirate city this week in solidarity with Saudi women preparing to take the wheel on Saturday. Agence France-Presse/Getty Images

Although no law explicitly prohibits women from driving in Saudi Arabia, the government refuses to give them licenses.

A week earlier, the woman started up the family SUV shortly after dawn to drive through Buraidah. Her son, riding shotgun, proudly filmed his veiled mother driving and then posted it on YouTube.

Buraidah is home to some of the country's most conservative clerics and is seen as a bastion of opposition to social change in Saudi Arabia. Many here say the monarchy is moving too quickly on civil liberties.

Women in Buraidah typically cover their entire face as well as their hair when outside the home, a sign of their conservatism. Many men in the town wear their red-and-white checked head scarf, or shemagh, hanging loosely, without the black cord around it worn by most Saudi men. It is a look worn by the country's most religiously observant men and by members of the Committee for the Promotion of Virtue and Prevention of Vice, the government-backed religious police.

For all its conservatism, however, Buraidah has seen all the elements of the kingdom's debate on whether Saudi Arabia should ease a women's-driving ban that both sides increasingly say is rooted in a conservative tribal heritage in which men make key decisions and a woman's honor is paramount.

"In religious terms, there's no problem with women driving. It's about our culture," said Saleh al Tuwaijari, a 29-year-old government worker who adamantly opposes women driving.

"We are Bedouins."

Campaigns to undo the prohibition on Saudi women driving date back to 1990. A group of women who drove in 1990 were denounced by name in newspaper stories and headlines, they and their families were subjected to career setbacks and government travel bans.

In 2011, during the peak of Arab uprisings around the Middle East, a Saudi woman named Manal al-Sharif revived a driving campaign from 1990 by posting a video on YouTube of herself at the wheel and urging other women to drive. Authorities jailed her for more than a week.

In both 1990 and 2011, clerics publicly denounced women drivers as prostitutes.

Saudi still has some of the harshest restrictions on women in the world. By law, Saudi women must have male guardians throughout their life. They are not allowed to vote in municipal elections, though Saudi King Abdullah bin Abdulaziz al Saud has said the government will lift that prohibition in 2015.

On Saturday, women are encouraged to drive themselves to work or to other errands. But supporters are not calling for any rallies or public gatherings to avoid challenging a government ban on protests.

The Interior Ministry broke its silence about the revival of the campaign on Wednesday, saying it would "firmly and fully enforce the laws."

The statement was ambiguous enough, however, that both members of the campaign and a countercampaign took to social media to declare victory.

About 100 clerics gathered outside the royal court in the capital Riyadh on Tuesday to denounce "Westernization" and what they called the "conspiracy" of women driving.

King Abdullah often is seen as a cautious progressive, at least in Saudi terms. In 2009, he created the country's first coeducational university, and removed a top cleric who objected to the mixing of genders.

In June, the king changed the official weekend to Friday and Saturday instead of Thursday and Friday with a week's notice, overriding decades of objections from conservatives who maintained that the country with Islam's holiest sites, Mecca and Medina, shouldn't share a weekend day with Christians or Jews. Also this year, he appointed the first 30 women to the monarchy's advisory Shoura Council, three of whom filed a recommendation for the council to study the full legalization of women's driving.

In Riyadh, psychotherapist Madeha al Ajroush, a veteran of women's driving campaigns of 1990, 2011 and now 2013, said she no longer cares about all the debate surrounding the issue.

With the revival of the campaign this year, a Buraidah cleric charged that women who drove could damage their ovaries and give birth to deformed children.

"It's irrelevant to me," said Ms. Ajroush. "All I know is that I'll be out" driving Saturday.

In Buraidah, Mr. Tuwaijari was among a cluster of Saudi men crowding the counter of a KFC outlet after the daily closing for afternoon prayer. He methodically ticked off six reasons for his objections to women driving. None was religious.

Like many Saudis, the first concern he cited was that in a culture where women's movement outside the home are often circumscribed, Saudi men would accost a woman out in her car.

"A woman alone?" he asked incredulously.

Saudi women must rely on male relatives, pay for a driver, or stay home.

In Buraidah, a 52-year-old retiree with blue-green knit slippers on crippled feet described her lot under the prohibition.

With no money for a driver, no children left at home to care for her, and no freedom here to take a taxi without a male relative to travel with her, simply keeping herself in groceries was a "struggle," she said.

She wept as she described reading the tweets of relatives decrying the driving campaign.

"I am a prisoner," she said, pinching together her veil beneath her moist eyes.

If the king would allow women to drive, "I would be the first," she said.