Business reporter Lina Saleh Ibrahim is the latest Syrian journalist to go missing.
The 31-year-old who works for the state-owned daily newspaper Tishreen has been missing for seven days. She was last seen leaving her Damascus home on 25 October.
On the same day, Wael Yousef Abaza - a freelancer who writes for several newspapers and Arabic news websites - was also reported to have disappeared in Damascus.
Their families have reported their disappearances to Syrian authorities but have not had a response.
Similarly, there is no information about Hussein Ghrer, a prominent blogger who vanished after leaving his home on 24 October.
A few days before, Ghrer wrote on his blog: "Silence doesn't serve us after today. We don't want a country where we get imprisoned for uttering a word. We want a country that embraces and welcomes words."
The New York-based press freedom watchdog, the Committee for the Protection of Journalists (CPJ) believes Ibrahim, Abaza and Ghrer are in state custody, but it has not been able to confirm their detention.
Mohamed Abdel Dayem, CPJ's Middle East and North Africa programme coordinator, said: "The government must immediately clarify whether it is holding these journalists, and if so, why."
Several journalists have been detained by authorities since unrest erupted across Syria in March, and many remain in custody.
Three freelancers - Omar al-Assad, Rudy Othman and Hanadi Zahlout - were arrested on 4 August and have not been heard from since. A fourth, Amer Matar, was arrested on 3 September in Damascus.
All four remain in detention without charge.