BRUSSELS, July 25 -- Climate activists staged protests against fossil fuels in several European airports on Wednesday and Thursday, causing flight cancellations and operational disruptions. Several protesters were arrested.

On Thursday morning, climate activists at Germany's largest airport in Frankfurt caused the cancellation of around 140 flights, with more disruptions expected throughout the day, according to airport operator Fraport. "We condemn the actions in the strongest possible terms and reserve the right to take legal action against the perpetrators," a spokesperson said.

The protesters, including the Last Generation group in Germany, are urging governments to commit to completely phasing out fossil fuels by 2030.

"The continued extraction and burning of oil, gas, and coal is a threat to our existence," Last Generation posted on social media platform X, criticizing the government for "throwing oil on the fire of the climate crisis."

Similar protests occurred on Wednesday at Cologne/Bonn Airport in the German state of North Rhine-Westphalia. German Interior Minister Nancy Faeser condemned the activist's actions, labeling them "dangerous, stupid and criminal."

"Those who block runways not only risk their own lives but also endanger others and harm all travelers," Faeser said on X.

In London, the Metropolitan Police arrested 10 Just Stop Oil protesters on Wednesday, outside London's Heathrow Airport and other locations, referring to their campaigns as a threat to summer travel.

According to the police, Just Stop Oil had previously stated it wanted to "disrupt national aviation and planned to target Heathrow."

Chief Superintendent Ian Howells, who led the operation, called the activists' protest "extremely reckless and would have represented a risk to the traveling public." He said the police arrested the protesters to avoid flight suspensions and make sure thousands of passengers and businesses, including hard-working families can go on their summer holidays.

At Oslo Gardermoen International Airport, climate activists organized by Folk mot fossilmakta (People Against Fossil Power) attempted to block the check-in area on Thursday morning, local media outlet Dagbladet reported.

Urging the Norwegian government to commit to halting the extraction and burning of oil, gas, and coal by 2030, this is the second day the group sought to interrupt airport operations. On Wednesday, three members of the same group disrupted air traffic by occupying the runway at Oslo Airport.

In Helsinki, members of Life Extinction briefly blocked entry to the security controls at the airport on Wednesday, both in the morning and afternoon, demanding the Finnish government stop subsidizing air travel.

Due to police intervention, most demonstrators withdrew after about 15 minutes. One person was detained for refusing to leave, police said. Moreover, police reports indicate that demonstrators attempted to paint the floor at the terminal entry in the afternoon but were stopped by the police. Airport operator Finavia said no flights were delayed, and customers could bypass the demonstration.

At Vienna Airport, four climate activists spilled paint in the check-in area of the airport's one terminal on Wednesday and protested by holding up signs that read "Oil Kills." Due to quick police intervention, no further disruption was registered.

Vienna Airport said in a statement that the protesters would be held liable for property damage. It added that "disruptive actions do not contribute to climate protection, but only lead to the destruction of public discourse," Austrian broadcaster ORF reported.

Several European nations have prepared regulations to mitigate the impact of climate activists' protests on air traffic.

Last week, the German government decided to tighten the penalties for obstructing air traffic, which still has to be approved by the parliament. Instead of a fine, climate activists will face up to two years in prison for such actions.

Earlier this month, the UK High Court granted an injunction prohibiting anyone from entering, occupying, or remaining on London Heathrow Airport land without consent concerning environmental campaigns. Anyone breaching the injunction might be jailed, fined, or have their assets seized for contempt of court.

In late April, the Group of Seven countries agreed on a timeline to phase out coal completely by the mid-2030s.