HS2 will provide a £15 billion boost to the UK economy every year after it is built, the Government claims.
Transport Secretary Patrick McLoughlin will argue the network will relived the pressure on Britain's transport system and insist the project will be completed within its £42.6 billion budget.
"The main reason we need HS2 is as a heart bypass for the clogged arteries of our transport system," McLoughlin will say.
Ministers are attempting to bolster support for the train link, which will connect London with Birmingham, Leeds and Manchester, after it came in for withering attacks from the influential Public Accounts Committee.
The Government launched a "fightback" today over controversial plans for the HS2 rail link promising a £15 billion boost to the economy.
The Prime Minister and Transport Secretary have launched what they refer to as a "fightback" over the HS2 high-speed rail project.