Boris Johnson has been urged to keep his promises after a report suggested the North is set to receive more than £2,300 less per person in transport spending than London.
The Government's planned transport spending for London is almost three times more per head than the North unless investment in the Northern Powerhouse gets the go-ahead, a think-tank said.
That figure rises to seven times more per person than in Yorkshire and the Humber or the North East, according to the IPPR North research based on Government figures and published on Monday.
Its analysis said the capital will receive £3,636 in transport spending per person, while the North will receive £1,247 in planned spending.
The study also suggested that the spending gap had widened over the last decade, with the boost in London being 2.5 times more than in the North.
IPPR researcher Luke Raikes said:
These figures show that the Prime Minister must urgently follow through on his promises to invest in northern transport infrastructure and devolve power to the North's leaders.
Shadow transport secretary Andy McDonald said:
The North is held back by Government under-investment in transport and a lack of powers over public transport, including poor rail connectivity and cuts to bus services.
Andy Burnham, the mayor of Greater Manchester, said the Government should be ''embarrassed by the growing disparity between the North and South.''
In the five years since they first promised us a Northern Powerhouse, the transport spending gap between North and South has widened and is set to get even wider over the next decade.
A spokeswoman said the Government ''did not recognise these misleading figures''. They went onto say:
We're spending more on transport per person in the North than anywhere else.