The Department for Transport has said it "does not remark connected speculation" aft projected cost-saving plans for HS2 were reported.
According to The Daily Telegraph, drastic changes are being planned that would astir halve the fig of high-speed trains per hr - and services would question slower.
The paper reported that plans to tally services astatine up to 224mph are successful jeopardy arsenic officials determine whether to trim maximum speeds.
In response, a spokesperson for the Department for Transport told Sky News: "We bash not remark connected speculation.
"Spades are already successful the crushed connected the HS2 programme. It volition amended link regions crossed the UK, supply a greener enactment of question and is supporting tens of thousands of jobs.
"We stay committed to delivering the project. We proceed to enactment successful enactment with the Integrated Rail Plan."
The proposals are reportedly portion of an overhaul - codenamed Project Silverlight and Operation Blue Diamond - arsenic ministers grapple with immense inflationary pressures connected Britain's biggest infrastructure project.
In a 2020 study conducted by erstwhile HS2 and Crossrail president Sir Doug Oakervee said up to 10% of gathering costs could beryllium saved if the request for specified ace precocious speeds was abandoned, the paper writes.
HS2 explained: What is it and however overmuch volition it cost?
As a result, lawman president of Sir Doug's review, Lord Berkeley, wrote a missive to Chancellor Jeremy Hunt and Transport Secretary Mark Harper - stating that, if speeds were reduced to 125mph, important amounts of wealth could beryllium saved.
"Why bash you request to get to London 30 minutes quicker erstwhile you person WiFi and your laptop connected the train?" helium said.
"I suggest that ministers should look astatine options for radically cutting the costs of what is near of HS2."
But the imaginable of cuts has been criticised by advocates of the project, the Telegraph reported.
As good arsenic cutting costs, HS2 Ltd, the government-owned company, has been accused of utilizing an "untested, out-of-date, fundamentally flawed" instrumentality to measure its interaction connected nature.
The Wildlife Trusts published a study claiming determination volition beryllium "at slightest 17% little quality present" aft operation of Phase One betwixt London and Birmingham, whereas HS2 Ltd "say determination volition lone beryllium a 2.6% quality loss".
Dr Rachel Giles, grounds and readying manager astatine Cheshire Wildlife Trust and writer of the study called for the institution to "urgently recalculate" the full nonaccomplishment of nature.
But a HS2 Ltd spokesperson said: "We don't recognise the figures from the study nor bash we judge them to beryllium reliable".