Lisbon on Tuesday condemned Venezuela's decision to slap a three-month suspension on Portuguese airline TAP for allegedly allowing an uncle of opposition leader Juan Guaido to carry explosives as he traveled with the politician.
Venezuela had announced the ban a day earlier on the flag carrier's operations to and from Venezuela, accusing it of allowing Juan Marquez to hide the explosives in his luggage.
"All this is unacceptable, incomprehensible and intolerable," President Marcelo Rebelo de Sousa told Portuguese media.
Foreign Minister Augusto Santos Silva also condemned the "unfriendly act" against a country that "stands out for its balance and its ability to talk to everyone."
Marquez was arrested upon arriving in Caracas from Lisbon with Guaido last week after a trip to the United States and Europe.
Announcing the suspension of TAP for "serious irregularities", Venezuelan Transport Minister Hipolito Abreu said it could become a permanent ban.
Diosdado Cabello, a top ally to President Nicolas Maduro, said Marquez was detained for allegedly carrying C-4 explosives hidden inside flashlights and perfume refills, and was wearing a bulletproof vest.
Cabello accused TAP of violating international norms by allowing Marquez "to import explosives".
Maduro's government also accuses TAP of hiding Guaido's name from the official passenger manifest and using a false identity for him.
Elliott Abrams, the US official leading the push to oust Maduro and install Guaido, scoffed at the allegations which he described as part of a campaign against the opposition leader.
"Like the jailing of Juan Guaido's chief of staff, Roberto Marrero, this is an obvious and vicious effort to attack Guaido's closest advisors and his family," Abrams told reporters in Washington.
TAP said it did not understand the reasons for the airline's suspension and complained that it had not had the chance to defend itself.
Venezuela's government is under harsh US and EU sanctions.
More than 50 countries recognise Guaido as acting president in the South American country following Maduro's 2018 re-election, denounced by the opposition as rigged.
TAP was one of the few foreign airlines still operating flights to and from Venezuela since 2013 when the price of oil -- the source of 96 percent of the country's revenues -- began to plummet.
Some 300,000 to 400,000 Venezuelans trace their ancestry to Portugal.