Papua New Guinea's National Intelligence Organisation maintains that there are questions over the authenticity of entry claims of some foreign workers.
The NIO is appealing for more stringent checks on workers entering PNG.
The agency is concerned that workers for projects such as the Ramu Nickel construction in Madang may be entering without proper security, customs and immigration checks.
The Chinese company running the project, Ramu NiCo, denies the claims and says it complies with PNG's laws.
However, the NIO's Bob Nenta says a lot of foreigners enter PNG citing major companies like RamuNico as their sponsor, but not all are genuine.
"We are just wondering as to the genuineness of these claims on the entry cards. So many people are saying that they're for Ramu Nickel and we are asking: are they all landing in Ramu? And that's the kind of line of our question. We said that we're becoming concerned about the influx of people and we're asking that maybe we should do one more check to make sure that they're going there."