Papua New Guinea's government has declared emergencies in three provinces following the first outbreak of polio in the country in 18 years.

World Health Organisation officials confirmed the outbreak this week after a six-year-old boy from Morobe province, northeast of the capital Port Moresby, was found to be carrying the virus.

The country's National Executive Council has now declared Morobe, Madang and Eastern Highlands infected areas and the government says it has approved $A2.7 million for a response.

Staff from international health organisations have been on the ground delivering immunisations and collecting samples.

The Pacific island nation had been declared polio-free since 2000 and joins Afghanistan, Pakistan and Nigeria in battling the virus.

Local health authorities declared an official outbreak after the US Center for Disease Control found the virus present in the stool samples of two children from the boy's neighbourhood.

The contagious and crippling disease mainly affects children under 5 years of age. It cannot be cured, but can be prevented with vaccination.