Foreign Minister Pekka Haavisto (Green) has said Belarus' explanation of why it forced a passenger plane carrying an opposition activist to land appear to be untrue.
Haavisto also told Yle's morning TV show Ylen Aamu that sanctions against the country, controlled by autocratic leader Alexander Lukashenko, were an option.
Haavisto added that he had been in contact with Belarusian counterpart Vladimir Makeyh on Sunday, describing the latter's explanation of the incident as "fragile".
"Belarus's explanations are very fragile. [Makeyh] referred to the threat of a bomb and I asked how it was possible for a passenger to remain at the airport, detained by the authorities. This does not happen in the course of a regular bomb threat, it seems to be a made up thing," Haavisto said.
The plane, a Ryanair flight from Athens to Vilnius, Lithuania, was forced to land in Minsk by a Belarusian fighter jet on Sunday. The reason for the unscheduled landing was initially reported as being a threat of a bomb on board the aircraft.
A Belarusian activist and journalist, Roman Protasevich, who was on the flight, was among those reportedly detained on landing in Minsk.
According to Belarusian news agency BelTA, the order came directly from President Lukashenko.
New sanctions on the cards
Haavisto described the incident as "shocking".
"This is completely against all aviation regulations and safety norms. It would be abnormal if the airspace of one European country was no longer safe," he said.
The incident has received widespread condemnation from European leaders, with EU Commission President Ursula von der Leyen calling for sanctions against those responsible. The issue is due to be discussed at an EU summit later on Monday.
"Such an event will trigger a strong reaction on the part of Europe when it comes to air safety. Individuals in Belarus have already twice been sanctioned over violence. It would be reasonable to think that, if the events have been as described, they would lead to new sanctions against Belarus and the individuals involved," Haavisto said.