Chancellor George Osborne has urged Chinese investors to bid for the seven HS2 construction contracts between London and Birmingham, worth a total of £11.8 billion.
They cover cover bridges, tunnels and earthworks on the first phase of the controversial link between the capital, the West Midlands and the North.
Mr Osborne is in the Chinese city of Chengdu during a five-day tour designed to strengthen Britain's economic links with the east Asian giant and win trade and investment for the UK.
The HS2 announcement comes shortly after Mr Osborne took a trip on one of the many high-speed lines that have been laid around China in recent years, from Urumqi to Turpan in remote Xinjiang province.
But anti-HS2 campaigners have attacked George Osborne's decision to launch the bidding process to build the high speed rail line.
They believe it is too early and he should not initially encourage China to pitch for the £11.8 billion contracts.
HS2 Action Alliance said the announcement confirmed that it is a "political project rather than a transport project."
The £43 billion proposed scheme has attracted criticism because of its cost and its impact on the environment and local communities.