Christian Climate Action (CCA), the Christian arm of the Extinction Rebellion, has said "sorry" for the disruption to train services in parts of London after a backlash from angry commuters.
Extinction Rebellion was forced to apologise for targeting the London transport network during rush hour on Thursday morning after one of its activists was pulled off the top of a train at Canning Town station.
The activist had climbed on top of the train with another campaigner using a ladder and unfurled a banner saying "Business as usual = death".
Passengers were forced to leave the train, causing many to react in anger, with the men appearing in video footage to be kicked and verbally abused by some of those on the platform.
Protesters, among them Christians, also targeted trains at Stratford and Shadwell.
Fr Martin Newell, a 52-year-old Catholic priest from Birmingham, and Rev Sue Parfitt, a 77-year-old Anglican priest from Bristol, climbed on top of a City-bound train at Shadwell station.
A third member of the group, Phil Kingston, an 83-year-old ex-parole officer, superglued himself to the side of the train before kneeling down with two other members of the group to hold a prayer vigil.
The protests caused the Jubilee and DLR lines to be partially closed.
Before the action, Fr Martin said: "We are acting to raise the alarm in a spirit of repentance for our complicity in sins against God's earth and God's poor. Parliament has declared a climate emergency but environmental issues were virtually absent from the Queens speech. We need action not words."
The protests have been "strongly" condemned by London Mayor Sadiq Khan, who earlier in the week said that he was "particularly angry at those targeting the London Underground – which would be extremely dangerous and counterproductive".
Nick Cooper, a shoemaker from Northampton who took part in today's protests, said that the activists "don't want to be causing disruption".
"We are not disruptive people; we are desperate people," he said.
"For so many years we have been writing letters to our MPs, signing petitions and joining in marches to draw attention to this climate emergency at our doorsteps. We don't know what else to do.
"We are so sorry to anyone whose day to day lives are affected but sadly economic disruption is the only thing which those in positions of power will listen to. This train was destined for the City, which is one of the economic powerhouses of the world."
Five members of CCA were arrested during the protests on Thursday.
Before he was arrested, Mr Kingston said: "I am doing this to ring the bell about the enormously dangerous situation our children and grandchildren are in.
"Greta Thunberg in her UN statement said we have eight years in which to reduce CO2 emissions to stay within the 1.5 degree limit. So emissions need to be falling rapidly today.
"In fact, 2017 and 2018 saw record rises in emissions. For our descendants, for the poorest peoples and Gods other-than-human creation, there is so much suffering happening - now destined to get worse without huge national and international response."
Later in the day, in a statement posted to Twitter, it said: "We have spent a lot of time blocking roads and are not being heard. People are dying now because of the climate crisis and it threatens all we love.
"We are sorry for disrupting the lives of ordinary people - we are desperate and don't know what else to do."
In its own statement, Extinction Rebellion apologised and said it was committed to non-violence.
"Following our previous statement on this morning's London transport actions, we would also like to apologise to all those whose lives we disrupted this morning," it said.
"We have spent a lot of time thinking about how best to respond.
"Extinction Rebellion remains fully committed to non-violence. The climate and ecological emergency is the biggest threat facing us all today, and it is unfortunate that something like this has to happen for this to become 'newsworthy'.
"That said, we are all incredibly sad at how events unfolded this morning, and are using this as an opportunity to learn and reflect as an organisation."
A YouGov poll found that members of the public largely opposed Thursday's train protests.
Asked who their sympathies lay more with, 63% said with the commuters who dragged the protesters off the train as opposed to only 13% who sympathised with the protesters.