Two Saudi women who spoke out on social media about the country's ban on female drivers are being tried in an anti-terrorism court. 

Loujain al-Hathloul, 25, and Maysa al-Amoudi, 33, were detained for nearly a month in defiance of a ban on females driving before being referred to an anti-terrorism court, reported The Associated Press. 

"Saudi authorities are ramping up their crackdown on people who peacefully criticize the government on the Internet," Human Rights Watch recently warned, according to AP.

The group also said judges and prosecutors are using "vague provisions of a 2007 anti-cybercrime law to charge and try Saudi citizens for peaceful tweets and social media comments."

The women have been in custody since Dec. 1, which is the longest period of time thus far for any women who opposed the driving ban. 

Human rights activists in Saudi Arabia are fearing that the country is using al-Hathloul and al-Amoudi as an example to deter others from taking a stance against bans, reported AP. 

The ban on female drivers in Saudi Arabia is informal - it was put forth by ultraconservative Saudi clerics, reported AP. The religious edicts are followed by authorities in the country, as women are not permitted to be issued driver's licenses. 

One activist believes that the ban on women drivers is more than just keeping women off the roads, but is also part of "a wider effort to quash any chances of raising the ceiling on civil liberties," reported AP.

There has been no comment from a Saudi official so far on the arrests.