Chinese companies are among those being urged to invest in building the HS2 rail link – which is due to run through south Northamptonshire.
Chancellor George Osborne’s opened bidding on the London to Birmingham section – with work expected to begin in two years.
Under EU law, foreign investors will have to partner with British firms.
But, Joe Rukin from the campaign group Stop HS2 is questioning China’s record on rail projects.
He says they have a history of corruption, delays and accidents.