The "Northern Powerhouse" will not be become a reality unless there is substantial new investment in a 21st century transport system linking its great cities, the North's political and business leaders have warned.

Delegates at the Northern Transport Summit in Leeds were told the region's "huge economic potential" was being held back by "an outdated, expensive and slow transport system".

The event was held after a series of rail links in the North, Wales and Midlands were downgraded last month at the same time the Government was announcing its backing for a new £30 billion Crossrail 2 scheme in London.

But Transport Secretary Chris Grayling argued that while improving northern transport links was one of his "biggest priorities" they must be "designed and managed by the North itself".

Among the speakers on Wednesday was Greater Manchester Mayor Andy Burnham who also urged the Government to "play your part of the bargain" in the promised Northern Powerhouse.

He said: "We are patriotic people in the North. We are proud of our capital city. We want it to have a 21st century transport system but it is not too much to ask the same for ourselves.

"The truth is we are London-centric as a nation. Too centralised. Devolution in the region is beginning and I think this could be a change for the better but it is up to us to grab the opportunity and fill that space with our passion to improve the North of England. To improve the prospects of life chances of people who live here.

"What I would like to see today is a plan that we can all begin to get behind, a campaign, because we do need to pool our influence and begin to use it on the national stage."

But Mr Burnham said partnership with Government was essential, adding: "Because we can't do it on our own. We will do our bit and will get our own act together.

"The message should go out today that the North is getting organised and we are getting serious. It is not a threatening message. It is about saying to the Government 'now you play your part of the bargain'.

"We will develop a plan. We are going to need your backing to make it real. After all, you did promise us a Northern Powerhouse.

"Help us now make it a reality."

He pointed out that travel times from Greater Manchester to some parts of the North had not improved since the 1960s.

"It takes four minutes longer to travel by train from Manchester to Chester than it did in 1962," he said. "I think that pretty much makes for why we are here today."

In a group statement, the regions' leaders said: "The North's huge economic potential is being held back by an outdated, expensive and slow transport system.

"The idea of a 'Northern Powerhouse' driving forward a rebalanced UK economy in the 21st century was supposed to right this wrong and is still supported.

"A successful North means more jobs, a stronger tax base, better inward investment opportunities and greater success for business for the whole of the UK. But none of this will be realised unless there is substantial new investment in modern infrastructure linking the great cities of the North.

"Recent statements by the Transport Secretary have sent worrying messages that this essential investment may not be delivered in full, with some key commitments dropped or substantially delayed.

"We believe that people across the North have waited long enough for transport services on a par with other parts of the country. The disparity between transport in the North of England and London must now be addressed."

The summit called on the Government to honour in full commitments already given to deliver improvements to rail services across the North, prioritise its manifesto commitment to deliver new west-east rail infrastructure across the region and to set out a fairer distribution of transport funding across the country.