Media playback is unsupported on your device Media caption Teachers' pay and rail franchising could be devolved, the UK government says

The UK government says it does not believe there is a case for "radical" changes to Welsh devolution.

The Conservative-Lib Dem coalition also suggests responsibility for policing, broadcasting and large energy projects should be retained at Westminster.

Its submission to the second part of the Silk Commission looking at the scope of the assembly's powers says arrangements are largely satisfactory.

But it says teachers' pay and rail franchising could be devolved.

The current devolution boundary in respect of the Wales and the Border franchise means that the in-franchise financial risk sits with the Welsh government but the financial risk of a new franchise (and catastrophic failure) remains with the UK government UK government submission, On the rail franchise

The commission, set up by UK ministers, is examining the current devolution settlement and is due to report next spring.

Opposition parties are pointing to differences of opinion between the Conservative-Liberal Democrat coalition in Westminster and Tories in Cardiff Bay.

Teachers' pay and conditions are currently decided at an England and Wales level and the document says they could be devolved "as a logical consequence" of deregulation in England.

Welsh ministers have previously said that they would rather the issue remain at an England and Wales level.

Media playback is unsupported on your device Media caption The UK government says it does not believe there is a case for "radical" changes to Welsh devolution

The Wales rail franchise, held until 2018 by Arriva Trains Wales, requires Welsh and UK ministers to sign the contract under current arrangements.

The submission says: "The current devolution boundary in respect of the Wales and the Border franchise means that the in-franchise financial risk sits with the Welsh government but the financial risk of a new franchise (and catastrophic failure) remains with the UK government. We believe this is undesirable."

It adds: "The Department for Transport is in discussion with the Welsh government to assess the feasibility of devolving franchise responsibilities, the financial and legal requirements of doing so and how the UK government's interests in services affecting locations in England could be protected."

The paper suggests that the Silk Commission could examine whether powers over the key M4 and A55 trunk roads in Wales, currently entirely devolved to Welsh ministers, could become a joint responsibility with the UK government.

It says: "The commission may wish to consider whether current arrangements for the maintenance and upgrade of these routes in Wales could be improved, particularly in the context of responsibilities for large-scale projects to upgrade and improve these routes."

However, the UK government is lukewarm on many of the areas that Welsh ministers have called for to be devolved.

On the devolution of policing, the submission says the current non-devolved system is working well, and lists several difficulties with making it the responsibility of the assembly.

The UK government's evidence provides the Silk Commission with a thorough and objective analysis of the Welsh devolution settlement which, I hope, the commission will find useful David Jones MP, Welsh Secretary

These include the fact that policing is "inextricably linked" with the criminal justice system, and the cost and complexity of separating out national structures and arrangements and the management of national threats.

At the moment, responsibility for consents to energy projects such as wind farms and power stations is only devolved up to 50MW onshore and 100MW offshore. Decisions on schemes larger than this which require ministerial approval are taken in Westminster.

The UK government signals in its evidence to Silk that it wishes to see this split continue, saying the current arrangements are "appropriate".

It says: "Many schemes above 50MW are of sufficient importance and scale to be considered nationally significant. Major infrastructure projects onshore between 50MW and 100MW include onshore wind farms, biomass plants and energy from waste plants.

"Changing the threshold from 50MW to 100MW could have a negative impact on energy and planning policy for major infrastructure and result in increased complexity in the planning system and less efficient, more piecemeal and more expensive development."

'Firm foundation'

The paper also says that responsibility for renewable subsidies should remain with the UK government, as well as regulation of electricity, gas and nuclear, and energy efficiency schemes which require regulation.

It says there are "arguments for and against" the devolution of youth justice, but points to the costs of any potential devolution of the judiciary, prisons or the courts service.

There have been calls to devolve responsibility for the two Severn bridges towards the end of the decade. The submission says this should be considered separately, outside the commission's discussion.

Welsh Secretary David Jones said: "The next stage of the Silk Commission has the potential to make an important contribution to ensuring a firm foundation for the longer-term governance of Wales within the United Kingdom.

"The UK government's evidence provides the Silk Commission with a thorough and objective analysis of the Welsh devolution settlement which, I hope, the commission will find useful as it undertakes its work."

A Welsh government spokesman said: "We will read the UK government's evidence with interest, but of course it must be for the Silk Commission to form its own view on the issues which it raises.

"We will be happy to assist the commission further as necessary."