RIYADH, Saudi Arabia (AP) -- A report given to a high-level advisory group in Saudi Arabia claims that allowing women in the kingdom to drive could encourage premarital sex, a rights activist said Saturday.

The ultraconservative stance suggests increasing pressure on King Abdullah to retain the kingdom's male-only driving rules despite international criticism.

Rights activist Waleed Abu Alkhair said the document by a well-known academic was sent to the all-male Shura Council, which advises the monarchy. The report by Kamal Subhi claims that allowing women to drive will threaten the country's traditions of virgin brides, he said. The suggestion is that driving will allow greater mixing of genders and could promote sex.

Saudi women have staged several protests defying the driving ban. The king has already promised some reforms, including allowing women to vote in municipal elections in 2015.

There was no official criticism or commentary on the scholar's views, and it was unclear whether they were solicited by the Shura Council or submitted independently. But social media sites were flooded with speculation that Saudi's traditional-minded clerics and others will fight hard against social changes suggested by the 87-year-old Abdullah.

Saudi's ruling family, which oversees Islam's holiest sites, draws its legitimacy from the backing of the kingdom's religious establishment, which follows a strict brand of Islam known as Wahhabism. While Abdullah has pushed for some changes on women's rights, he is cautious not to push too hard against the clerics.

In October, Saudi Arabia named a new heir to the throne, Prince Nayef, who is a former interior minister and considered to hold traditionalist views, although he had led crackdowns against suspected Islamic extremists. His selection appeared to embolden the ultraconservative clerics to challenge any sweeping social reforms.

Prince Nayef was picked following the death of Crown Prince Sultan.