Sir Bill Cash said the massive cost of dealing with Covid-19 means Britain can not afford to plough billions of pounds into the controversial high speed rail project.
Chancellor Rishi Sunak has pledged what he called "one of the most significant economic interventions at any point in the history of the British state" in response to the coronavirus crisis, including paying the wages of millions of workers and stumping up £330 billion worth of loans and guarantees.
Economic forecasters have warned the measures could plunge the UK into the biggest recession in modern history, and Sir Bill says ditching HS2 would represent a major saving for the Treasury.
"HS2 is going to cost a lot more than £100 billion, and in fact I've even seen figures quoted of £200 billion," the Stone MP said.
"If the Government wants to benefit the health service during the crisis, then it would be far better to keep this kind of money in the accounts."
Sir Bill has vowed to continue the fight against HS2, despite it being signed off by MPs after a review recommended that it should proceed in full.
It's final bill is expected to hit £106bn – more than treble its original budget – although critics say it is likely to be far higher due to delays and rising costs.
The first phase of HS2 will run from London to Birmingham. Phase 2a is due to carve through 45 miles of Staffordshire countryside on its way to Crewe, before subsequent sections take passengers from Crewe to Manchester, as well as Birmingham to the East Midlands and Yorkshire.
Last week Lord Berkeley, a vocal opponent of HS2, published a letter to the Prime Minister and Transport Secretary Grant Shapps calling for the project to be paused for six months.
He said HS2 workers on site were "clearly being put at risk of infection by failure to observe the social distancing rule", and also urged the Government to reconsider its decision to press on with the scheme.
"I am sure that ministers will want to look at the finances for HS2 and/or its cheaper alternatives in the light of the Government’s unexpected expenditure on supporting business and people as a result of the coronavirus, before deciding whether to allocate over £100bn to HS2," he said.