LONDON (AP) — Environmental activists who have repeatedly blocked Britain’s busiest highway face possible imprisonment after a judge granted an injunction against the protesters, Britain’s transport secretary said Wednesday.

Members of campaign group Insulate Britain have shut down parts of London's M25 highway, which circles the British capital, five times in just over a week by sitting on the ground, painting the name of their group on the road and raising placards in front of traffic. Some have also targeted other highways.

Police have arrested dozens of the protesters, who demand the government improve home insulation to reduce emissions from heating and powering homes.

“Invading a motorway is reckless & puts lives at risk,” Transport Secretary Grant Shapps wrote on Twitter. “I asked National Highways to seek an injunction against M25 protestors which a judge granted last night.”

The injunction means that activists will face contempt of court with possible imprisonment if they continue blocking roads.

Insulate Britain spokeswoman Zoe Cohen said protesters “understand that the risks they are taking are because that we have tried everything else to make the government protect us from the predicted impacts of climate chaos.”

“That involves the loss of all that we cherish, our society, our way of life and law and order,” she told BBC radio.

Cohen said her group wants the government to update insulation in social housing by 2025 and all homes by 2030, “because this is the most effective way to reduce emissions and save lives from fuel poverty.”

The group said it will end its campaign as soon as it hears a “meaningful commitment” by the government to its demands.

The High Court order, which officially came into force on Wednesday, prohibits anyone from “blocking, endangering, slowing down, preventing, or obstructing the free flow of traffic onto or along or off the M25 for the purposes of protesting.”

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