Greenpeace has defended its anti-oil protest following criticism of a “major security breach” at Rishi Sunak’s constituency manor house in North Yorkshire.

A group of activists have been bailed by North Yorkshire Police after a demonstration on the roof of the Prime Minister’s grade II-listed mansion on Thursday.

North Yorkshire Police, which has come under fire following the incident which took place while Mr Sunak and his family are on holiday abroad, said their investigation “remains ongoing”.

The campaigners draped his home with an oil-black fabric to protest against the Government’s plans to grant more than 100 new licences for oil and gas extraction in the North Sea.

Areeba Hamid, co-executive director of Greenpeace, said the protest had been planned “carefully and meticulously” and would not have gone ahead if the Prime Minister was there.

She told Sky News it was a “proportionate response to a disastrous decision” by Mr Sunak to allow for further drilling.

Ms Hamid said the activists had knocked on the door and got a response before making it clear to those present who they were.

“Security is a big part of whatever we do, we planned it carefully and meticulously, we knew he wasn’t going to be there,” she said.

Protesters scaled the roof of Mr Sunak’s home at about 8am while the Prime Minister and his wife and children are on holiday in California, and stayed up until around 1.15pm, when they were arrested.

North Yorkshire Police said: “All five suspects who were arrested following the protest in Kirby Sigston on August 3 have been released on conditional police bail to allow for further inquiries to be carried out.

“The investigation remains ongoing.”

Assistant Chief Constable Elliot Foskett said: “There was no threat to the wider public throughout this incident, which has now been brought to a safe conclusion.”

But a former deputy chief constable from the force said it was a “major breach of security”, as he called for an “investigation into how this has been allowed to happen”.

Mr Sunak, the MP for nearby Richmond, this week announced plans to “max out” the UK’s oil and gas reserves by granting more than 100 new licences for extraction in the North Sea.

Protester Alex Wilson, who lives in Newcastle with her partner, who was also on the roof, released a video message from the scene, saying: “We’re all here because Rishi Sunak has opened the door to a new drilling frenzy in the North Sea while large parts of our world are literally on fire.

“This will be a disaster for the climate.”

On the ground, Greenpeace UK climate campaigner Philip Evans defended the action at the Prime Minister’s family home.

Asked whether it was intrusive to target someone’s home, he said: “This is the Prime Minister. He is the one that was standing in Scotland going to drill for every last drop of oil while the world is burning.”

Peter Walker, who stepped down as North Yorkshire Police’s deputy chief constable in 2003, said he was “absolutely astonished” the protesters gained access to the house, as he called for an investigation.

He told LBC radio: “It is clearly in my view a major breach of security.”