HS2 will deliver "the step change in capacity" needed to support growing demand from both passengers and freight, according to the head of the transport committee.
Chairwoman Louise Ellman said if taxpayers were to reap the full benefits of HS2, it was "vital" links were improved between regular and high-speed rail networks.
We remain confident that construction of a new high speed line is the only way to deliver the step change in capacity on the West Coast Main Line needed to accommodate long-term demand for both passengers and rail freight.
If we are to spread the benefits from HS2 as widely as possible, it is vital we improve links between the conventional and high-speed networks and bring forward projects to speed up journey times on the conventional network.
– transport select committee chairwoman louise ellman
A group of MPs are "convinced" the controversial HS2 link between London and the north is "justified" and urged the Government to consider building the second and first phases together.
Abandoning the project "significantly outweigh the risks" of building it, as the high-speed rail link is "essential for the UK", according to the transport committee.
Phase one, from London to Birmingham via the Chilterns, is due for completion in 2026, with a second Y-shaped section from Birmingham to north-west and north-east England due to be finished in 2032/33.
In its report, the committee said: "Many important local issues will be debated and resolved by the (HS2) hybrid bill committee and there will be detailed debates about many aspects of the project.
"However, we are convinced that it is essential for the UK for HS2 to go ahead, and to do so as a project which has the backing of all three major political parties."
The report into the viability of HS2 is a "cheerleading whitewash" and only heard from "people who support" the London to Birmingham rail link, according to activists.
Campaign manager for the Stop HS2 group Joe Rukin said:
Unlike the public accounts committee and treasury committee hearings on HS2, it was clear that this inquiry was going to be a cheerleading whitewash when the transport committee only called people who support HS2 to give evidence.
Despite the official cost of HS2 standing at £50 billion, the committee want to pretend it is £28 billion, even though they said it would be £34 billion in 2011.
In saying this and telling the DfT they should abandon their standard assessments to improve the case for HS2, they are effectively ordering the Government to 'spin harder' on HS2.
It is "essential for the UK" that HS2, which will link the Midlands with London and the north, goes ahead says an MPs' report.
The House of Commons Transport Committee's report also says the risks of not going ahead with the project "significantly outweigh the risks of doing so."
The committee, chaired by Labour MP Louise Ellman, also said serious thought should be given to building the second-phase of the line - which will run to the north from the East Midlands - at the same time as the first phase London-to-Birmingham stretch is being built.
The report also calls on the Department for Transport to emphasise that the estimated cost for HS2 is £28 billion, not £50 billion, due to contingency costs.
The first phase of the scheme, from London through the Chilterns to Birmingham, is due for completion in 2026.