City region plan for Cardiff, Newport and Bristol unveiled
Details on how Cardiff, Newport and Bristol plan to work together as a city region under the title of Great Western Cities have been unveiled.
It is hoped the move will boost the economy in the region and help to develop renewable energy.
The announcement is the latest step for councils either side of the Severn Estuary to work together to rival England's 'northern powerhouse'.
The cities involved have already formed partnerships to shape transport plans.
In November, the leader of Cardiff council warned that the capital would lose out if it did not work with another major centre like Bristol.
The launch report said the three cities were already amongst the most successful in Britain, with a combined economic output of £58bn, but could do better.
It said investment in the region must focus on improving connectivity, realising the "energy potential" of the Severn Estuary and Bristol Channel and promoting the region as a high-quality destination for international business.
The RSA City Growth Commission, which looked at how to develop cities' economic growth, identified the Severn region as one the the six powerhouse "super-city regions" in the UK.
Phil Bale, Cardiff council leader, said the Great Western Cities region would be complementary to the Cardiff Capital City Region, and if it did not go ahead Cardiff would lose jobs and investment.
He added it was "not in any way" in conflict with the Welsh government but was about creating jobs, which the government would want to see.
Newport council leader Bob Bright said it would be about working as a unit to bid for funding from the UK government, and that the cities "can't be isolationist".
Bristol's mayor, George Ferguson, said the combined cities were the best economic powerhouse outside London.
It would be "crazy" not to have a faster rail service between Bristol, Newport and Cardiff, he added.
Welsh Secretary Stephen Crabb said: "By working together our great cities can pack a bigger economic punch to support business and private enterprise."