Papua New Guinea's Prime Minister says the private jet which transitted through Port Moresby carrying two controversial Vanuatu diplomatic passport holders was checked thoroughly by officials.
The two were Charles Henry Saken and Pascal Anh Saken, the owner of the super yacht Phocea which has been detained in Vanuatu since last July when it was seized on suspicion of passport fraud and drugs trading.
After arriving last Thursday, the jet's passengers reportedly met with Vanuatu's Foreign Minister Alfred Carlot who, according to Vanuatu's government, was in Moresby on a private mission.
PNG officials briefly detained the passports of the passengers and Mr Carlot.
Peter O'Neill says they had reason to believe some of the passengers on the plane had questionable backgrounds, requiring a background check.
He says the jet departed Sunday night after an investigation by officials.
"And they concluded that they have not breached any particular laws of our country other than not getting proper clearance for the plane to land in our country. The host country that has given the diplomatic passports to these persons have requested that they be allowed to transfer through our country and of course we have no choice but to comply with that."