A St John's spokeswoman said the ambulance service was put on alert.
Part of the secure Customs sector was cordoned off after the man arrived shortly after midday because of the "suspicious article", airport spokesman Richard Llewellyn said.
Llewellyn said the security scare had not affected any other flights. "It has slowed the processing of arrivals but it hasn't closed [arrivals]. One of the lines has been cordoned off and the number of processing staff has been reduced," he said.
"We do ask people to be patient and I'm sure police and Customs will go through their processes as quickly as possible." Police said no decision had been made by aviation security whether to lay charges against the passenger.
Two years ago, a traveller flew in from Tahiti with a loaded handgun in his luggage. Baptiste Julien Jeune, 69, got the Bauer .25-calibre gun through Customs and it was only found as he passed through MAF checks before leaving the airport.