Cities which elect mayors this year should push for “metro mayors” covering multiple local authorities in 2016, according to a leading think tank.

The Centre For Cities warned that mayors whose authority was limited to just one local authority would not have the powers they needed to create jobs and grow the economy.

They should be allowed to take control of transport and planning policy – which would mean governing on a “city region” basis.

In the case of Birmingham, which is holding a referendum on whether or not to create a directly-elected mayor on May 3, this would probably mean creating a single directly-elected leader for the West Midlands conurbation, including Birmingham, Solihull and the Black Country including Wolverhampton. It might involve Coventry as well.

However, any such proposals are likely to meet stiff opposition from the towns and cities surrounding Birmingham, where civic leaders have traditionally resisted any moves which look like they could lead to the creation of a “Greater Birmingham”.

Alexandra Jones, chief executive of Centre for Cities, said: “Centre for Cities’ data provides a snapshot of the size of the job mayors will face in the cities that elect them.

“Like council leaders, they will have a big job to do and it still remains to be seen what powers will be devolved to mayors.

“At the very least we think they should make decisions over transport and planning that are of strategic importance for growth.

“This is where effective decision making can really shape the economic fortunes of cities.”

“In the short term, mayors will need to focus on building excellent relationships with neighbouring authorities to ensure that decisions on major planning, skills and transport policies are not restricted by political boundaries.

“By the time of the next electoral cycle in 2016 we hope that national government will allow those cities with the appetite for it to introduce metro mayors.”