The wrong side of the tracks: Lobbyists for HS2 rail line funded by the taxpayer

Campaigners against the expensive project accuse the coalition of 'underhand misuse' of money

The estimated cost of the HS2 rail link continues to rise (PA)

The Government has been accused of "resorting to the underhand misuse of taxpayer money" to pay for lobbyists to promote HS2, as pressure mounts on the coalition to scrap the £42.6bn rail project.

Leading politicians have lined up in recent days to criticise the growing cost estimates for a railway that will reduce the journey time from London to Birmingham to 49 minutes and create more than 100,000 jobs. Most prominently, the former transport secretary and chancellor Alistair Darling has described the project as a potential "nightmare", having supported HS2 when he was in office.

Critics are now scrutinising the Department for Transport's use of a lobbying firm, Westbourne Communications, to help to promote a railway that would eventually have 330 miles of track but has divided the public. HS2 Ltd, the body set up to steer the project, spent more than £80,000 on using Westbourne to July, while the DfT paid the London-based firm a further £24,000.

There are also two Westbourne staff on secondment to HS2 Ltd, who, according to rail minister Simon Burns in a recent parliamentary answer, are "specifically working on the promotion of HS2". So far, taxpayers have spent £84,480 on these two staff.

Campaigners against HS2 argue that this has stacked the argument against them financially. The news also comes after David Cameron watered down his tough rhetoric against the lobbying industry with a Bill that critics have dismissed as "a dog's breakfast".

Hilary Wharf, director at HS2 Action Alliance, told The Independent on Sunday: "I think this is appalling. The Government is resorting to underhand misuse of taxpayer money to push through this programme. This shows the weakness of their argument and discredits their position. David Cameron and George Osborne will soon be the last two men left standing in support of HS2."

Buried in a highly critical Institute of Economic Affairs report last week, which claimed HS2's cost could eventually soar to £80bn, is a scathing assessment of the use of Westbourne and film-maker Tomboy Films. The latter was paid £86,000 to produce two short information videos.

The report said: "A significant proportion of HS2-related lobbying appears to be state-funded, raising important questions about government effectively using taxpayers' money to lobby itself."

Questions have been raised over the possibility of a conflict of interest at Westbourne. The firm also advises Birmingham airport on its expansion proposals, which would link up with HS2 in what has been described as "an integrated transport hub for the Midlands providing high-speed domestic and long-haul international connectivity".

A source close to HS2 said that a distance between the two clients was maintained as Westbourne worked directly for the airport but put staff on secondment for HS2. Ms Wharf argued that "Chinese walls are very difficult to maintain at a lobbying business".

Before being hired by the DfT, Westbourne ran an independent campaign to drum up support for HS2 between February 2011 and January 2012, which included its own battle bus.

The protest groups themselves have been accused of using taxpayers' money to fund their campaigns. The 51M coalition of councils has spent more than £1m of taxpayers' money to fight the Government's plans, while Buckinghamshire Council has handed HS2 Action Alliance £10,000 towards the group's Supreme Court appeal against HS2 this coming October.

A pro-HS2 source argued: "The City millionaires, aristocrats and tax-funded shire councils of the anti-HS2 campaign have spent millions on PR, QCs and lobbying to undermine a project that was a manifesto commitment of all the major parties. It really takes the biscuit when they complain about efforts to mobilise the country behind a project of national economic significance."

However, Ms Wharf insisted that all other contributions had come in private donations of £5 and £10 a time. "I would have loved to have had one or two wealthy benefactors, but it hasn't turned out that way," she said.

Westbourne director James Bethell said: "Clear communication is an essential responsibility of modern major infrastructure programmes like HS2 to ensure the project reaches its potential. Westbourne is proud of our communications advice which we have provided in a cost-effective, transparent manner and meeting relevant government guidelines."

An HS2 spokesman said: "We are putting in place a long-term communication strategy to publicise the benefits of what will be the single biggest infrastructure project the UK has undertaken in decades. HS2 Ltd does not lobby government. We are governed by clear rules and our communications programme has been subject to the scrutiny of, and approval by, the Cabinet Office. Furthermore, our staff, including those on secondment from other organisations, are bound by strict confidentiality agreements. All HS2 Ltd expenditure is reported to Parliament."