As Kem Ley’s hearse left Wat Chas pagoda shortly before dawn last year, inching across a bridge spanning the Tonle Sap amid throngs of mourners, Hun Dimo was there, watching.

The 43-year-old farmer was hundreds of kilometres away in Kampong Thom province. None of the country’s television stations, private or state-run, were broadcasting the assassinated political analyst’s funeral procession. Yet Dimo joined millions of others who watched the event not from the streets, but from their phones – through a live feed from Radio Free Asia staffed by dozens of their reporters.

This kind of access to the free flow of information is being hampered – perhaps critically – by an experiment Facebook is now running in Cambodia and five other small countries, according to local media organisations, NGOs and analysts.

Facebook’s tweak pulls posts made by official pages – including those from news organisations, politicians and NGOs – out of the News Feed and into a hard-to-find section called Explore Feed.

The change, which was launched on October 19, has already resulted in loss of traffic for RFA, Voice of America and local NGOs, even though it is not readily apparent to users.

“A regular citizen like me isn’t paying attention to [the changes to the news feed],” said Dimo, who said he had not realised that posts from RFA and VOA, which he follows, had been moved. “Maybe only those with social media skills noticed.”

That is precisely the fear of publishers, many of whom say the experiment is particularly devastating because the experiment coincides with an unprecedented crackdown on opposition voices in recent memory, which has seen the blackout of RFA and VOA, the closure of the Cambodia Daily, the shutdown of critical NGOs and the jailing of citizens for Facebook comments perceived as critical of the armed forces, the prime minister or the ruling party.

In response to criticism over the change, News Feed product head Adam Mosseri explained in a blog post last week that the company is testing the feature because people “want an easier way to see posts from friends and family”.

But Sutawan Chanprasert, a legal researcher for Columbia University’s Global Freedom of Expression Project, said Facebook now represents more than a way to catch up with friends.

Facebook “is a channel where people can exercise their freedom of expression”. Chanprasert said. Now, she said, “the opportunities for people to hear independent political and media voices will be less. RFA and VOA, for example, have disseminated their news on Facebook mostly since the shutdown. Their news feed will not reach people easily any more unless they pay.”

The number of Cambodians turning to the internet for news is increasing rapidly, according to studies. Last year, for the first time, more Cambodians said they received their news from Facebook and the internet than they did from television, according to a study conducted by the Asia Foundation and Open Institute.

RFA’s live broadcast of Ley’s funeral – which was streamed over Facebook, YouTube and their Khmer website for 13 and a half hours – was viewed 28 million times across the three channels.

In an email yesterday, VOA spokeswoman Anna Morris expressed apprehension about the Explore Feed test and said that traffic had dropped at VOA Khmer since the start of it.

“We believe that weakened access to reliable news is not in the best interest of average Cambodians,” Morris said, noting that many Cambodians access VOA’s content through Facebook.

RFA spokesman Rohit Mahajan also acknowledged that RFA had seen a drop in traffic after the change, although he declined to elaborate further.

“We will have to see [what happens],” Mahajan said. “But the timing isn’t ideal.” Not only are the changes hurting traffic for independent voices; they are also affecting the government’s preferred medium for interacting with the public.

Facebook is used extensively by public officials in Cambodia to make announcements and raise their profiles – none more so than Prime Minister Hun Sen himself, who has 8.9 million Facebook fans, making him one of the most followed world leaders.

Social media managers for Hun Sen did not respond to requests for comment. The premier regularly shares not only political announcements but also selfies and workout shots on his page.

He has also used his follower count to taunt critics like former opposition leader Sam Rainsy, who the premier has mocked for having less than half the total of his followers.

Facebook’s experiment makes no distinction between supporters and critics of the government, meaning that posts from Hun Sen and Rainsy both end up in the same hard-to-find feed.

But according to Rainsy, Facebook’s Explore Feed hurts opposition voices more than the ruling party because the opposition cannot access mainstream broadcast media in Cambodia.

He and other CNRP leaders used Facebook heavily to garner grassroots support ahead of their strong showing in the 2013 national election.

“Facebook’s latest initiative would possibly give an even stronger competitive edge to authoritarian and corrupt leaders with massive financial means thanks to systemic corruption,” Rainsy said, noting that traffic on his page has dropped 20 percent since the launch of Explore Feed.

The change has also shaken small to medium-sized NGOs, who say that they rely on Facebook to advertise and disseminate information cheaply and are seeing plummeting engagement.

Melanie Mossard, community director at social enterprise Impact Hub, expressed concern that the change will crush what was a burgeoning marketplace for startups and activists. Since the start of the experiment, the average reach on their Facebook page has dropped 60 percent, she said.

“All the people I know managing a Facebook page in Cambodia are sharing the same frustration,” Mossard said. “People forget about this new channel and are not used to checking the new button yet.”

Jaime Gill, a communications consultant who works with several NGOs in Cambodia, said cash-strapped NGOs rely on Facebook as a fundraising tool.

One of his clients, Tiny Toones Cambodia, an NGO that works with marginalised youth, had just built a critical mass of followers with the help of a few viral videos, Gill said, when Explore Feed launched and engagement with Cambodian users dropped by three-quarters.

“It’s important to see Cambodians supporting other Cambodians,” he said. “And knowing that that has just been made so much harder, as I said, is just depressing.”