A Melanesian Spearhead Group observer team says all polling stations it visited in Papua New Guinea's election had too many incidences of names missing from the common roll.
The MSG observers have issued an interim statement, as the vote counting stage of PNG's lengthy election is underway across the country.
It said "the 2017 PNG National Elections were fully embraced by PNG citizens, even though it presented many challenges".
In all the polling stations that were visited by the seven MSG observers, the voters were described as "excited to participate in the election" but many found their names had dropped off the roll, or not been added.
The statement, which also noted instances of double voting with concern, was the precursor to a final detailed report with recommendations to be released later.
"We noticed and acknowledge that the absence of an official voter identity card made it difficult for officials both to ascertain and to ensure that no one under 18 years was voting as well as to prevent the urge for double voting," read the statement.
Voter identification, the MSG said, remained a major issue for both voters and officials and its determined resolution would greatly assist in the transparency of the entire election process.
"We noted that this was happening, especially when the Organic Law on national and local level government elections already provided for the use of tools such as a computerised, electronic and photogenic system of voting and identification for an inclusive and transparent process for citizens to exercise their democratic rights in any election.
"It will require strong political will to ensure that the election system is continually updated, improved and strengthened."
The MSG observers statement said the team also observed long delays in the opening of polling stations on polling days.
"In fact, no polling station we visited ever opened on time at 8 am.
"During the counting period there were long unexplained delays before the official counting started - in several instances well over two to three days and in one case well over six days.
It appeared that there was confusion over certain election counting processes which may have resulted in the delays.