Campaigner says detentions in Jeddah are first significant action by authorities against women who are challenging ban

At least five Saudi women have been arrested after defying the kingdom's ban on women drivers, an activist has said.

For the past two weeks Saudi women have been driving through the capital, Riyadh, and other cities in a challenge to the ban.

Eman al-Nafjan, a Saudi-based rights activist, told the Associated Press that police detained five women on Tuesday as they drove in Jeddah on the Red Sea coast. There was no new information on the status of the detainees.

"This is the first big pushback from authorities it seems," Nafjan said. "We aren't sure what it means at this point and whether this is the start of a harder line by the government against the campaign."

Saudi women involved in the campaign have said they want the restrictions lifted in a country where women can only appear in public escorted by a male relative.

Saudi Arabia has no written law barring women from driving – only fatwas, or religious edicts, issued by senior clerics following a strict brand of Islam known as Wahhabism.

The group Saudi Women for Driving has said its campaign is inspired by the Arab uprisings against autocratic rulers and appealed for high-level western backing.

The US secretary of state, Hillary Clinton, has praised the protesters, while stressing they are acting on behalf of their own rights and not at the behest of outsiders like herself.

The Saudi protests have put the Obama administration, and Clinton in particular, in a difficult position, with Saudi Arabia being a close US ally. The administration supports greater freedom for Saudi women but is increasingly reliant on Saudi authorities to provide stability and continuity in the Middle East and Gulf amid uprisings taking place across the Arab world.