The UK Government announces plans to electrify the line from Cardiff to Swansea, as well as several Valleys lines
There are reports that UK Transport Minister will announce a £1bn project to electrify the railway lines in south Wales.
Theresa Villiers will visit the Welsh Assembly to discuss rail electrification for Wales, but isn't expected to announce further plans.
Following today's meeting between the Welsh and UK Governments in London, Carwyn Jones says he's willing 'to meet some of the incidental costs' of rail electrification in the South Wales Valleys.
But in a sign that this dispute is far from over, he told Political Editor Adrian Masters that 'we're not paying for the whole thing, there's no chance of that.'
The First Minister has challenged the UK Government to publish documents it says prove the Welsh Government agreed to pay the costs of rail electrification in the South Wales Valleys.
Carwyn Jones was speaking to Political Editor Adrian Masters following a meeting in London of the Joint Ministerial Committee which brings together leaders of the devolved nations, chaired by the Deputy Prime Minister Nick Clegg.
Both sides in the rail electrification costs row remain polarised, if you'll forgive the pun, after today's Joint Ministerial Council meeting. A Whitehall source said it seemed the First Minister had 'picked a fight to hide his embarrassment' about an agreement, the existence of which he disputes.
For his part Carwyn Jones has challenged the UK Government to produce any document which would prove a deal. Until now the correspondence has only been semi-leaked but I understand there are moves to try to publish it.
The First Minister says he'll consider paying for some 'incidental costs' but not the full costs. He also told Nick Clegg that one solution would be to devolve responsibility - and the funding - for rail to Wales immediately. Neither side show any signs of backing down.
The First Minister is expected to raise the dispute over funding for rail electrification in the South Wales Valleys at a meeting in London. Carwyn Jones will attend a session of the Joint Ministerial Committee which brings together the UK Government with leaders of devolved governments.
These meetings, which are chaired by the Deputy Prime Minister Nick Clegg, take place regularly and usually cover a wide range of topics that are causing tension between the governments.
I'd be amazed if Carwyn Jones didn't seize the opportunity to return to the disagreement which has soured relations between ministers in Cardiff and London more than any other previous dispute.
On the day the Chancellor has insisted that the Welsh Government DID agree to share funding of rail electrification in the South Wales Valleys, opposition parties have kept up the pressure. Catch up with the background to this increasingly bitter row by clicking here.
Welsh Conservative leader Andrew RT Davies said Carwyn Jones' government should be 'eating humble pie.' Plaid Cymru's Simon Thomas feared that if the costs end up being met through increased ticket prices the 'Valleys Metro idea is out of the window.'
But the leader of the Welsh Liberal Democrat leader Kirsty Williams found cause for optimism in what she said was 'the more conciliatory tone' taken by the transport minister Edwina Hart. Ms Williams said she's hopeful a way forward can be found and said that would be
– Kirsty Williams AM, Leader of the Welsh Liberal Democrats
best achieved by going back and working with the UK Government rather than having a bloody great row between the First Minister and Prime Minister.
UK Government sources say they're 'shocked and concerned' at the First Minister's call for 'clarification' over who'll foot the bill for rail electrification. It's understood the dispute focusses on the Valley Lines, the Franchise for which is the Welsh Government's responsibility.
The UK Government says an exchange of letters from 2012 between the then Transport Minister Justine Greening and Carl Sargeant, who was then the Welsh minister responsible, shows the Welsh Government agreeing to bear initial costs of Valley Lines electrification.
The agreement would see those costs recovered from the Wales and Border Franchise. A UK Government source told me that the government 'is shocked and concerned that almost two years after agreement evidenced in writing the Welsh Government is seeking to deny that any such agreement was reached.'
The First Minister says he's 'now concerned about the UK Government's intentions' over funding for electrification of the main London to South Wales railway line and the Valleys Lines.
Carwyn Jones said he still doesn't have confirmation from the UK Government that it will pay the full cost of electrification despite assurances from the Prime Minister and Welsh Secretary. He said ministers and officials continue to try to gain 'clarification' on the situation.
A new train maintenance plant will be built in Swansea, after a £4.5billion deal for new intercity express trains was announced by the UK Government today.
Under the agreement, Agility Trains, a consortium led by Hitachi of Japan, will build 596 rail carriages at a new factory in County Durham.
The Intercity Express Programme (IEP) project will see the current fleet of Intercity 125 trains replaced.
On the Great Western Main Line from London to Swansea, the new trains will enter service in 2017.
Together, the new trains and infrastructure will offer the potential for journey time savings of 15 minutes in Swansea to London journeys.
– Transport Secretary Justine Greening
A new train factory is fantastic news for Britain and will be welcomed by everyone who wants to see a thriving UK manufacturing sector.
Businesses in Swansea have welcomed the announcement that the railway line from London will be electrified.
Local business owners are planning to make the most of the new rail links, and hope that the new infrastructure will encourage more business development in the area.