SEAPA, a regional media freedom advocacy group, made the calls as media activists around the world commemorate the International Day to End Impunity, which falls on the anniversary of 2009's Maguindanao massacre.
The Alliance's executive director, Gayathry Venkiteswaran, told Asia Pacific the day is to remind the public that each year a large number of people - villagers, journalists, bloggers, cartoonists, songwriters, lawyers and human rights defenders - are being stifled through the use of unjustified legal actions or violence.
"The Southeast Asia Press Alliance has been monitoring the kinds of threats faced by journalists and we have seen a trend where the threats have grown both in terms of violence as well as the use or the unjustified use of law to persecute those who use media spaces for expression," she said.
She says this year alone there has been more than a 100 cases involving various threats against journalists, with some members of the media even losing their lives.
"Now in 2009 there was one of the major cases of 32 media workers who were killed in Maguindanao in Southern Philippines...that was one of the bleakest days really in terms of safety of journalists in the region," she said.
"But we see that has not actually stopped the kind of threats and violence against journalists."
Ms Venkiteswaran says while there is a "renewed hope" for free expression with the expansion of media spaces, Southeast Asia still has a way to go.
"I think [there are] fundamental issues about those in power [and] how they can maintain that power, regardless of which political side they are on," she said.
"I think that continues to be a very, very volatile issue and the major victim here is really the media."
Ms Venkiteswaran cites Indonesia as one country that has potential to lead the way toward greater press freedom in the ASEAN region.
"I think they have a rather robust legal environment that can afford support and protections for the media and also public access to information," she said.
"Implementation is another story but I think that they do have the right framework, you know, it's in the right direction."