Five Iranian crew members of a cargo plane grounded in Argentina since last week face an investigation into suspected links to Iran's elite Islamic Revolutionary Guards Corps, officials said.
A judge on Monday ordered their passports and other documents to be held for an additional 72 hours after Security Minister Anibal Fernandez said information had been received from “foreign organisations” that some among the crew may be linked to companies with ties to the IRGC.
The IRGC is on a US blacklist of foreign terrorist organisations.
A routine check found “things that were not logical”, Mr Fernandez told Perfil radio on Monday.
“They had declared a crew that was smaller than the one that travelled,” he said, adding the matter was “still under investigation”.
He said the five Iranians were in a hotel.
Officials originally said their passports were surrendered but would be returned if they left the country on a scheduled flight while investigations continued into the plane's origins.
The Venezuelan Boeing 747 cargo plane reportedly carrying car parts first landed in Cordoba, Argentina, on Monday last week. The crew tried to travel to Uruguay, but was denied entry and returned to Ezeiza outside Buenos Aires.
The crew included 14 Venezuelans, who were not detained.
Iran claimed on Monday that Argentina's decision was part of a “propaganda” campaign against Tehran when tensions with Western countries over negotiations to revive a 2015 nuclear deal were high.
The plane was sold by Iran's Mahan Air to a Venezuelan company last year, he said.
Mahan Air is believed by the US to have links to the IRGC.
It was designated by the US in 2011 for “providing financial, material and technological support to the Islamic Revolutionary Guard Corps-Quds Force”.
The US has claimed Iran has used Mahan Air for moving energy sector components to Venezuela for President Nicolas Maduro's government.
Mr Maduro visited Iran at the weekend, where he signed a 20-year co-operation deal on Saturday.
Like Iran, Venezuela has been subject to US sanctions, although they have covered fewer companies and individuals compared to those Washington has applied to Tehran.
Saeed Khatibzadeh, the spokesman for Iran's Foreign Ministry, told reporters the grounding of the plane was part of efforts seeking to “cause a feeling of insecurity.”
“These recent weeks are filled with propaganda, are full of psychological operations, these wars of words that want to infiltrate the minds and composure of the people,” Mr Khatibzadeh said.
“This news is one of those.”
The grounding of the plane came as a resolution was adopted by the International Atomic Energy Agency's board of governors to censure Iran for non-co-operation with its inspectors.
Talks in Vienna, under way since April last year, aim to return the US to a nuclear deal known as the Joint Comprehensive Plan of Action that it left in 2018.