An environmental campaigner has slammed the high-speed railway after a ‘giant’ sinkhole opened above HS2 works near a Buckinghamshire lake.

Campaigners have demanded HS2 to stop the tunnelling works after a huge crater-like hole appeared by the Shardeloes Lake in Amersham on Saturday (May 13).

The Environment Agency is now investigating the 6m (20ft) sinkhole on a field, which remains cordoned off for safety.  

The chair of River Chess Association Paul Jennings said he has feared an incident like this for more than 10 years.

READ MORE: Amersham: Sinkhole opens above HS2 tunnelling works

He said: “The message we got on Saturday didn’t come as a surprise and I wouldn’t be surprised to see more.

“We told it would be unwise to tunnel in this section and there would be a very good chance the fluids could find their way to the surface and pollute the river.

“The water could find its way into the tunnel, which could be extremely dangerous for the workers.

“I hate to be the person to say I told you so.”

One of his concerns was the use of stabilising chemical bentonite pumped to the tunnel walls, which he feared would end up into the aquifer.

“Our long term concerns haven’t changed – that irreparable damage will be done to drinking water source and damage to rivers.

“There’s concern that material might make its way to the surface but there’s also a lot of things that we won’t see and will make permanent damage, and finally here’s a serious danger to public health, safety, wildlife and people operating the tunnels.

He claimed the Environment Agency hadn’t monitored the project “very well”, relying on HS2 self-monitoring instead.

“What I would like to see is the Environment Agency to ask for full explanation and stop all tunnelling activity until there’s a full explanation and no danger to individuals, property and wildlife. Until they can satisfy that’s not the case, they should stop the drilling,” he added.

Buckinghamshire Council had been “very concerned about HS2 all around,” he noted.

“There’s destruction not only to the environment but infrastructure, roads are ripped up and complete disregard for people,” Mr Jennings said.

The council leader and Amersham resident Martin Tett visited the sinkhole on Monday (May 15) before holding an urgent meeting with senior HS2 directors over "what reassurances can they give that this will not happen again," he said on Twitter.