Parts of northern England have higher mortality rates than parts of Turkey, Slovakia and Romania, according to a think tank report which says "the UK is more regionally divided than any comparable advanced economy".
The "State of the North 2019" report, from IPPR North, blames centralisation of power and lack of devolution for makings the country more regionally divided than comparable nations like France or Germany in a range of areas like health, jobs, disposable income and productivity.
The report, published on Wednesday, says that only countries like Romania and South Korea are more divided.
It found that the disposable income divide is larger than any comparable country and has increased over the last 10 years.
It came as Tory Chancellor Sajid Javid and his Labour counterpart John McDonnell both visited neighbouring marginal constituencies in West Yorkshire as they aimed to woo voters with promises about boosting the northern economy.
And a senior Yorkshire business leader said the best way to unleash the collective potential of the North was to devolve powers to local leaders rather than encouraging them to compete for resources from central government.
According to the IPPR North report, in Kensington and Chelsea and Hammersmith and Fulham, disposable income per person is £48,000 higher than in Blackburn with Darwen, Nottingham and Leicester.
And it found that rates of mortality vary more within the UK than in the majority of developed nations with places like Blackpool, Manchester and Hull having mortality rates worse than parts of Turkey, Slovakia and Romania.
The report also said the divides in jobs opportunities and productivity are also larger than in comparable countries.
It said that parts of London and the South East are among the most productive in the developed world, whereas parts of Northern Ireland, Wales and the North of England are less productive than parts of Poland, Hungary and Romania.
The report authors blamed centralisation for the creation and worsening of these regional divides, saying that 95p in every £1 paid in tax is taken by Whitehall, compared with 69p in Germany.
They also said that one per cent of GDP is spent by local government on economic affairs, which is half as much as is spent locally and regionally in France or Germany.
Report author and senior research fellow at IPPR North, Luke Raikes, said: "It is no surprise that people across the country feel so disempowered. Both political and economic power are hoarded by a handful of people in London and the South East, and this has damaged all parts of the country, from Newcastle to Newham."
He said: "All our regions' economies have been held back by centralisation - but they're interdependent too and we can no longer ignore that.
"All our regions need devolution to be empowered, and to work together. This must be a top priority for the next government."
Co-author and interim director of IPPR North, Arianna Giovannini, said metro mayors in the north of England had "shown what's possible".
He said: "Devolution must be the way forward for the country, and all areas need substantial power and funding.
"The next government must lead a Devolution Parliament - an unprecedented and irreversible shift of power - so that England's regions, towns and cities can work together to bridge our regional divides."
Speaking to The Yorkshire Post on his way to a campaign stop in Meltham, part of the marginal Labour-held constituency of Colne Valley, Shadow Chancellor John McDonnell said the report exposed a "lack of consistent investment by central government."
He said his party's National Transformation Fund worth £250bn would be designed with the aim of tackling regional inequality by investing in better rail and broadband as well as alternative energy sources like solar, wind and wave power.
And he said a national investment bank based on the German model, with regional banks in the North, would ensure private sector funding is matched by public sector funding.
He said: "When decisions are made they will be made at local level, making sure money goes where it is needed. It is about devolution of power as much as devolution of resources."
Northern Powerhouse Minister Jake Berry said: "Since 2010 there are over half a million more people in work, wages are rising faster than inflation and over 100,00 more businesses have been created in the North.
"The Conservatives in government have done more than any other to maximise the power of the North. Five years ago there was no devolution at all, now 50 per cent of the people who live in the North are represented by metro mayors with a warchest of powers and money to drive jobs and growth.
"We are investing a record £13 billion into northern transport infrastructure. With a majority Conservative government, we will also build Northern Powerhouse Rail which will unleash the potential of our great towns and cities across the North."
Roger Marsh, who chairs the NP11 Board and Leeds City Region Enterprise Partnership responsible for promoting economic growth, said: “IPPR North is right to emphasise that empowering the North and other regions outside of London to collaborate with pounds and powers through devolution – rather than the current system which encourages competing for resources from the centre – is the most effective way to unleash our collective potential.
“The Manifesto for the North, produced by NP11 and Convention for the North, has set out a roadmap for how this devolution, aligned with investment in transport and skills, will help to address inter-regional inequalities, rebalance the UK economy, and place the North at the front and centre of tackling the climate emergency.”
Greater Manchester metro mayor Andy Burnham said: “Our London-centric parliament is the root cause of the deep North-South divide that scars our country, and by extension the wider divides in today’s politics.
“Westminster has become dysfunctional and is not providing the answers that the North needs. In the days that remain in the General Election campaign, we need to hear ideas for substantial political reform and the transfer of power out of Parliament and into the English regions.”