Leaders from the North of England have demanded a place at the Brexit negotiating table with Prime Minister Theresa May.
The leaders of five combined authorities said it was "absolutely vital" the north is heard during negotiations to leave the EU as its population is greater than London's and its economy is larger that Scotland's and Wales's.
They invited Mrs May to a meeting in Greater Manchester "at her earliest convenience".
A letter is signed by combined authority leaders, including Paul Watson, the chairman of the North East Combined Authority and leader of Sunderland City Council, and those in West Yorkshire, Greater Manchester, Liverpool and Sheffield.
It says: "Your efforts to meet leaders outside London is commendable.
"However, the North of England has long had concerns that we are being ignored, caught between an economically and politically powerful London and an increasingly politically important Scotland.
"As we negotiate our exit from the European Union, you have made clear that you believe in having an approach and negotiation objectives that include the whole of the United Kingdom.
"On that point we wholeheartedly agree. It is absolutely vital that the voice of the North of England is heard loud and clear during the Brexit negotiations.
"The North of England has a population greater than London and almost three times that of Scotland.
"Our economy is significantly larger than Wales' or Scotland's.
"Accordingly, we would like to invite you to meet with us at your earliest convenience to discuss our role within the Brexit negotiations and how we can work together for the benefit of the North."
The IPPR North think tank backed the letter.
Director Ed Cox said: "The North of England has a population of 15 million and an economy worth £300 billion - twice that of Scotland - and so it is right that Northern leaders should demand a place at the Brexit negotiating table and a North first approach to investment.
"The city leaders should be mindful though that it was outside the big cities that the strength of the Leave vote was strongest and for the 'northern powerhouse' initiative to prosper, greater thought must be given to how the North speaks with a more inclusive voice and develops a more joined-up economic plan."