Riyadh: Saudi officials stepped up warnings on Friday over plans by women to challenge the male-only driving rules in the ultra conservative kingdom, saying that even online support for the protest could bring arrest.

The warnings came on the eve of the planned protest by Saudi women activists who have obtained driver’s licenses abroad. The Internet has been a key tool in reaching out to international media and organising the demonstration, similar to one staged last year by a small group of women.

Though no specific Saudi law bans women from driving, the rules are enforced by Saudi clerics who hold far-reaching influence over the ruling monarchy and give it political legitimacy.

Mention of the strict Saudi laws against online political dissent significantly broadens the possible fallout from the expected campaign by Saudi women, who have pledged to get behind the wheel on Saturday in defiance of Saudi traditions enforced by the nation’s powerful Islamic religious establishment.

Friday’s edition of the pan-Arab newspaper Al Hayat quotes the Saudi Interior Ministry spokesman as saying cyber-laws could apply to anyone supporting the women driving campaign.

Conviction can bring up to five-year prison sentences and stiff fines, the article quoted a Saudi consultant on cyber laws, Marwan Al Ruwqi.

Saudi Arabia has adopted some reforms in recent years, including allowing women to sit on the national advisory council and a decision by King Abdullah to permit women to vote and run in municipal elections in 2015.

But the driving ban appears to retain the backing of senior clerics, who also refuse to amend codes such as requiring women to obtain a male guardian’s approval to travel.

Al Faisal, the ministry spokesman, was quoted as saying the cyber-dissident law “will be applied against violators”, while other measures will be taken against “those who gather to support” the planned protest.

On Wednesday, he warned of police crackdowns against “disturbing public order”. The statement was issued after about 150 clerics and religious scholars protested outside a royal palace, saying Saudi authorities were doing nothing to stop women flouting the ban.

Some of the leaders of the campaign said they received phone calls from authorities emphasising the warnings.

The main website of the women driving effort, oct26driving.org, was apparently hacked early on Friday and replaced with the message: “Drop the leadership of Saudi women.”

In Washington, State Department spokeswoman Marie Harf said the US supports “the full inclusion of women in Saudi society”.

“That would, of course, include driving,” she said.