CONSERVATION groups will be delivering a letter to the Prime Minister today calling for an HS2 tunnel to be extended - saying it will save more than ten hectares of ancient woodland.
David Cameron will be personally asked to intervene today, the final day of a consultation on the rail project's environmental statement.
Campaign groups say HS2 Ltd figures suggest 32ha of irreplaceable ancient woodland will be lost if building work on the line goes ahead - but almost a third of this can be saved by extending a tunnel through the Chilterns.
The letter - signed by the Woodland Trust, The Ramblers, Berks, Bucks and Oxon Wildlife Trust, Chilterns Conservation Board, Buckinghamshire County Council and Chesham and Amersham MP Cheryl Gillan - will be handed in at Downing Street at midday.
The campaigners say 10.2ha of ancient woodland - which has existed continuously for more than 400 years - can be saved if a tunnel through the Chilterns is extended by 10.4km from Mantles Wood, near Amersham, to Wendover.
HS2 Ltd engineers have confirmed this is technically feasible but the idea has been rejected due to cost.
But Hilary Allison, Woodland Trust Policy Director, said: "There is absolutely no excuse to bring a tunnel portal up into the middle of an irreplaceable ancient wood. Ancient woodland is a unique and irreplaceable habitat, widely recognised as having national importance and no amount of new planting would ever fully compensate for its loss.
"This tunnel extension is a sensible option and we hope to see government and HS2 Ltd give it proper consideration."
Steve Rodrick, Chief Officer of the Chilterns Conservation Board, added: "As both ancient woodland and the Chilterns Area of Outstanding Natural Beauty have been given national protection, how can it make sense to destroy them? A full length bored tunnel under the Chilterns to save these national treasures is desirable and practical."
Meanwhile, it's been claimed HS2 could lead to the extinction of a rare breed of protected bat in Bucks.
Researchers from the University of Leeds concluded in a report for the Berks, Bucks and Oxon Wildlife Trust that Bechstein's bats face 'local extinction' if no significant changes are made to the route of the line.
The report said there is "no evidence to suggest that any of the mitigation proposals...will be effective, and they may do more harm than good".
Matt Jackson, head of conservation strategy and policy at BBOWT, said the route of the line would "create a barrier" to the bats' movements through woodland.
He said: "Natural England will only grant licences for the building of HS2 if there is evidence that protected species will not be wiped out, but the scientific review suggests this is precisely what will happen unless major changes are made."