The police commander in Papua New Guinea's Western Highlands says the deliberate spilling of oil on the Kagamuga airport tarmac near Mt Hagen is an act of terrorism.

Because of the incident the airport was shut throughout Tuesday.

Superintendent John Sagom said the suspects entered the airport in the early hours of Tuesday and spilled oil on the tarmac.

He said it was an act of "terrorism" and has vowed to investigate the incident thoroughly and arrest those involved.

Commander Sagom is asking the general public to come forward if they have any information.

He said, "leaders have to be sensible and responsible. What is happening in Mt Hagen does not speak well for the local leadership if they are going to resort to such acts of terrorism, threats, force and intimidation to have it their way."

In the meantime, a heavy police and Defence Force presence has been mounted around the airport and within the Mt Hagen township area.

Mr Sagom says there was a brief moment of concern in Mt Hagen when protesters aired their grievances over the appointment and handling of the Mt Hagen Open returning officer's post.

He said leaders must respect the democratic election process and called on them to take control of the situation and work with the security forces.