LONDON - Environmental campaigners blocked parts of the M25 London orbital motorway on Wednesday, causing major disruption to some rush hour traffic around the British capital in their second such protest this week.

Insulate Britain, which is demanding that the British government gives a commitment to help provide insulation for 29 million homes, said more than 80 members of the group had blocked a number of junctions to the motorway, one of the busiest in Britain, as well as part of the carriageway itself.

Police, who have faced some criticism over their response, said they had made arrests and removed protesters. Insulate Britain said in a statement it would keep going until the government responded.

"In the meantime they can arrest us, they can put us in prison, we know who we are and what we have to do," it said.

Dozens of protesters were arrested by police on Monday when activists staged a similar protest at various points around the 117-mile motorway, causing hours of tailbacks and provoking fury from many motorists.

Some said how they had missed health appointments while others said hospital staff had been unable to get to work.

Surrey police said they had arrested some 25 people and London police said 11 arrests had been made by its officers.

"We understand and respect the right to protest, but not the right to cause disruption to the public in this way," London police said. "This affects critical national infrastructure and diverts many officers from responding to emergencies in their communities."

Insulate Britain was unrepentant.

"The people in cars are angry, they are outraged, they are disgusted. Rightly. What a thing to do. What stupidity. What idiots," it said. "So why are we doing it Because we are angry, because we are outraged, because we feel disgust beyond words."

(Reporting by Michael Holden; editing by Sarah Young and Emelia Sithole-Matarise) ((; +44 207 542 3213; Reuters Messaging: