In a statement, the Foreigners and Borders Service states that the 16 foreign citizens were detained for strong indications of the crimes of forgery or counterfeiting of documents.
SEF states that 13 people were arrested at Lisbon airport for using a fraudulent document when they tried to board a flight to Cancun and Istanbul.
At Porto airport, SEF detained two other foreign citizens for using someone else's fraudulent travel document during document control when leaving national territory, bound for Dublin.
In the Azores, at Ponta Delgada airport, a passenger was arrested for using a fraudulent travel document while trying to board to Toronto.
At Faro airport, SEF complied with a warrant for the arrest of a Portuguese citizen, coming from Birmingham, to serve an effective sentence of imprisonment of two years and eight months for aggravated theft.