Anti-HS2 campaigners are in “good” spirits after spending their fifth night holed up in tunnels under a central London park.

Protesters have dug a network of tunnels beneath Euston Square Gardens, next to Euston station, in a bid to protect the green space which they claim will be built over with a temporary taxi rank before being sold to developers as part of plans for the high-speed railway.

One activist, Larch Maxey, speaking to the PA news agency by phone on Monday, said conditions underground were “not too bad”.

He said: “Conditions are good. They are warm. They are a bit moist, there’s a little bit of water coming in, but it’s not too bad.”

“Our spirit is really good, we’re all working really well together and really grateful to take this stand.”

A spokesman for HS2 Rebellion, an alliance of groups and individuals campaigning against the planned high speed railway, confirmed there were a total of nine activists in the tunnels.

They include veteran environmental campaigner Swampy, real name Daniel Hooper, and his son Rory.

Conservative MP Andrew Mitchell told the Sun newspaper that Swampy was “reckless and irresponsible” for allowing his reportedly 16-year-old son to be in the tunnels.

A statement shared by HS2 Rebellion hit back at Mr Mitchell for “cynically” criticising a “brave father-son team”.

Mr Maxey, 48, a former geography lecturer and post doctoral researcher, claimed ongoing efforts to evict the group from the site were “unlawful”.

He said: “This is our home, we’re in a Covid pandemic, they shouldn’t be carrying out an eviction.

“We’re in a climate and ecological emergency. We have a right to protest and stop that happening.

Mr Maxey added: “it’s an unlawful eviction and it’s being carried out in an unlawful way because they are not following safety protocols and the due process, making sure it’s safe for everyone.”

He claimed that the tunnels were “safe” but some changes by bailiffs “increases the risk to us”.

It is understood protesters are considering legal action over concerns for their safety.

An HS2 Ltd spokeswoman said: “The Health and Safety Executive (HSE) has reviewed the operations to safely remove the activists.

“They reviewed our safe system of work and the qualifications and competencies of the eviction team there.

“The HSE inspector made no immediate observations during the visit as to improvements we need to make and we continue to plan and work to safely remove the activists.

“HS2 Ltd and our contractors undertaking this operation have met frequently with the HSE and will continue to do so until this challenging situation is resolved.”

An HSE spokesman said: “HSE is aware of the protest and is in liaison with HS2 in order to review any plans that would affect workers, protesters or rescue personnel.”

Mr Maxey also alleged that protesters been denied “all food and water” but still had supplies to last them “months”.

He said: “We’ve certainly been denied all food and water and often have not been able to pass on our waste either.

“It would be very good to have more to ensure we have healthy fresh food and water.”

No activists could be seen above ground on the protest site on Monday.

A fence surrounds the muddy Euston Square Gardens which features piles of debris, while a scaffolding and wood structure remains standing.

Security, enforcement officers and a small police presence were at the scene.

At the weekend HS2 Ltd warned activists “they are putting themselves in even greater danger” by not leaving amid worsening weather conditions.

On Friday the protesters said “liquid mud” was pouring into the tunnel system.

The Metropolitan Police said two arrests had been made on Friday under the Trade Union and Labour Relations (Consolidation Act).

Five others were arrested at the scene on Thursday, three for allegedly breaching Covid regulations.