Bougainvilleans have been encouraged not to take selfies while voting in their independence referendum.
A fortnight-long polling period is underway for the autonomous Papua New Guinea region's non-binding referendum.
The Bougainville Referendum Commission has called on voters not to take photos of their marked ballot papers and post them on social media.
The Chief Referendum Officer said a selfie could identify the voter and their vote - in both cases it undermined the secrecy of the referendum process.
Mauricio Claudio said that after waiting two decades to vote in a self-determination referendum, Bougainvilleans were understandably excited.
But he said international good practice included not identifying voters and their choices to the world through Facebook and other platforms.
Organic Law also compels the commission (BRC) to discount any ballot papers if electoral officers can identify who marked them.
"I am sure that these keen voters would be appalled to put their vote in jeopardy by a selfie."
The Chief Referendum Officer noted that while there was no specific law covering the sharing of people's marked ballots on Facebook, it was clearly not something that supported a credible process.
"The BRC is doing everything in this referendum by the book, following the laws and international good practice," Mr Claudio said.
"We have been appointed by the two governments to conduct an independent, credible process, and this includes maintaining the secrecy of the vote so that the final result is respected by all parties: voters, the two governments and the international community."
"The Commission appreciates the outstanding community conduct so far. People have come out to vote, and they have shown great respect for everyone's right to vote without intimidation, fear or favour."