ENGLAND'S biggest cities make a dramatic intervention in the independence debate today, insisting they want closer ties rather than "greater separation" from Scotland's main municipal centres.

The leaders of Birmingham, Bristol, Leeds, Liverpool, Manchester, Newcastle, Nottingham and Sheffield - who together form a group promoting their role in driving economic growth - call for more powers to create jobs and boost their local economies in a letter to The Herald.

The council chiefs argue the move would be "a more radical constitutional agenda than establishing a border at Carlisle".

Senior councillors and officials from the Core Cities Group, representing the cities, are due to meet in Glasgow today, the first time they have gathered outside England.

A "Glasgow declaration", set out in their letter and making the case for cities across the UK to co-operate on economic development, accompanies the highly symbolic gesture.

All of the eight cities are Labour-controlled except for Bristol, which is run by a rainbow coalition.

In the letter, the leaders say Britain's big cities share much in common, including their industrial past and a common future "as the drivers of the UK economy".

They add: "We feel at home in ­Glasgow, a great Scottish and British city. And, while the question of independence is one for the people of Scotland, we need to add our voices to those who believe that devolving more power to cities to let them create jobs and grow their economies is a more radical constitutional agenda than establishing a border at Carlisle."

Citing the proposed high-speed rail link between London and the north of England, the group added: "Our cities need better connectivity rather than greater separation.

"For example, by working together to deliver HS2 we will make life better for people and businesses in every UK city. This should be our shared vision."

The English council chiefs will meet at the City Chambers before staging a private Q&A for business leaders at the Emirates Arena Commonweath Games venue in the east end. They were invited by the leader of Glasgow City Council, Gordon Matheson.

Mr Matheson said: "The fact is that Glasgow has more in common with cities such as Liverpool and Manchester than we do with much of the rest of Scotland. I welcome this powerful intervention against separatism from my fellow city leaders.

"The issues they face from an over-dominant London economy and government centralism are the same that Glasgow faces. The answer is to radically devolve power and resources to city regions across Britain so we can grow our economies and make a bigger contribution to GDP; not to erect a border at Carlisle, create huge uncertainty over currency and regulatory frameworks, and turn people from Newcastle into foreigners."

Last month, First Minister Alex Salmond travelled to Carlisle and launched a charm offensive to reassure England's northernmost counties about the possible impact of independence on their region. Speaking on St George's Day, he said independence would give the north a boost by rebalancing a UK economy too heavily reliant on London.

He argued independence would create new opportunities for co-operation between Scotland and northern England and told council leaders, officials and business people they would remain "Scotland's closest friends, as well as our closest neighbours".

He proposed the creation of new "borderlands economic forums" if Scotland votes for independence.

Labour leader Ed ­Miliband has set out a competing vision for the UK's big cities, also acknowledging the need to tackle London's economic domination.

He has pledged a major devolution of powers and funding over housing, ­transport and skills training policy.

Mr Miliband said the UK had built its economy "far too much" on London.

The Scottish Government has said that in the event of a Yes vote in September's referendum it would host a series of special forums on economic co-operation with the north.