°®Âþµº

Loujain al-Hathloul shared news of her release via her social media accounts. 

"I have been released this afternoon (Saudi time) after three days of detention. Thank you all for your support and care," she said on her and Twitter accounts, adding a link to an Arabic song entitled "I breathe freedom" by Lebanese singer Julia Boutros.

Hathloul was arrested for a second time on Sunday over her activism challenging Saudi's strict laws on women. 

Amnesty International on Monday strongly condemned her detention. 

"It appears she is being targeted once again because of her peaceful work as a human rights defender speaking out for women’s rights, which are consistently trammelled in the kingdom," said Samah Hadid, the rights group's director of campaigns in the region.

In 2014, Hathloul was held for breaking an absolute ban in the Gulf kingdom on women driving - the only country in the world where women are not allowed to do so.

She tried to drive into the kingdom from the neighbouring United Arab Emirates in defiance of the ban, and was held for more than two months.

At the time, campaigners for Hathloul's release did not provide full details of the allegations against her but said investigations appeared to focus on social media use rather than driving.

Saudi citizens are highly active on social media including on Twitter, where many post anonymously under fabricated user names.

However, Hathloul's account, which has 284,000 followers, is run under her real identity.

Saudi Arabia, an Islamic absolute monarchy, has no female cabinet ministers and is the only country in the world where women are not allowed to drive.

Women have to cover themselves in black from head-to-toe in public, and require permission from a man in their families to travel, work or marry.