(CNN) -- Family members and friends of an Al Jazeera journalist detained last week in Syria were relieved when news of her whereabouts surfaced Wednesday, but they now have concerns as to when she will be released.
The Syrian government acknowledged holding Dorothy Parvaz, a reporter with the Al Jazeera English network, who had gone missing after arriving in Damascus on Friday to cover the ongoing unrest in Syria, the network said.
Syrian officials confirmed they were holding Parvaz but it was unclear how her case would proceed, said Sophia Quereshi, a spokeswoman for Al Jazeera.
"We are worried about Dorothy's welfare, security and safety. Syria should release her immediately," a statement released by the network said.
The Syrian Embassy in Washington did not respond Wednesday to CNN's calls seeking comment.
Parvaz's family members said they have had no direct contact with the 39-year-old since she disembarked from a Qatar Airways flight in Damascus last Friday.
"We're thankful for the official confirmation, it's a good first step which now allows U.S., Canadians and Iranian officials to take further action," said Todd Barker, Parvaz's fiance, of Luxembourg.
"We trust that they will be treating her with the respect that she deserves," said her father, Firouz Parvaz of Vancouver, Canada.
Parvaz holds US, Canadian and Iranian citizenship and has worked for Al Jazeera since 2010.
Kristen Young, a friend and former colleague with Parvaz at the Seattle Post-Intelligencer, said Parvaz had recently returned from reporting on the aftermath of the earthquake in Japan and had covered political strife in Iran.
On Monday, Iranian foreign minister Ali Akbar Salehi expressed his concerns regarding her detention to state-run TV, IRIB.
"I hope that it is not true, but if that is the case, then we demand the government of Syria to look into this," said Salehi.
Thousands of supporters from around the world have started a social media campaign on Facebook, "Free Dorothy Parvaz" and Twitter #FreeDorothy in an effort to draw attention to her disappearance.
"It's such a horrible situation, all you can do is take action," Young said."E-mail everyone you know, call everyone you know, put it on Facebook."
Syria has been roiled for six weeks by anti-government protests and has largely prevented foreign journalists from covering the unrest.
Media organizations have been relying on social media, eyewitness accounts and cell-phone video to report the story.
Dozens of international journalists have been detained and expelled from Syria since March 15, when anti-government protests began, said Mohamed Abdel Dayem, program coordinator for the Committee to Protect Journalists in the Middle East and North Africa.
Syria, according to the committee, has always been one of the worst countries in the region for local and international reporters. Dayhem called Syria's admission that it was holding Parvaz a positive development.
"The announcement that they are indeed holding any given journalist is usually a precursor to them being released and expelled. Those two things always go hand in hand. Every [international] journalist who has been detained since March 15, once they are released, they are expelled," said Dayem.
Dayem said a regime already restrictive of press freedoms has turned increasingly repressive.
"Syria has always been one of the worst countries in the region for local and international reporters. A bad situation has only gotten worse."