Rhondda MP Chris Bryant has resigned from his role as Shadow Leader of the House of Commons amid protest over Jeremy Corbyn's leadership.
He shared the news on his Twitter profile as well as sharing the resignation letter.
In it, he said he was grateful for the opportunity but criticised Corbyn for his stance during the party's campaign to remain in the EU.
Since taking up the post of Shadow Leader of the House I have worked as constructively as possible with you and your office.
Last week changed everything. A major plank of Labour's longstanding economic and foreign policy was defeated in the referendum and we effectively handed the right in this country their biggest victory in a century.
The Prime Minister must take the lion's share of the blame for that defeat and he has honourably resigned, but your inability to give a clear, unambiguous message to Labour voters significantly contributed to the result. You left many Labour voters uncertain as to our party's position.
With Brexit and a prolonged period of instability and uncertainty on the horizon, our country urgently needs inspiring leadership as it charts its way through very difficult waters. My constituents rightly look to Labour to provide that leadership but at the moment it is sadly lacking.
A Welsh MP has added his name to the list of senior labour figures calling on Jeremy Corbyn to step down.
Aberavon MP Stephen Kinnock has said the party would suffer heavy losses at a general election unless the leadership changes in the wake of the referendum vote to leave Europe.
He's also voiced concern over the impact the Brexit result may have on the steel industry.
Kathryn Tresilian reports:
Britain's decision to leave the European Union has not affected Liberty's interest in bidding for Tata Steel, ITV Wales understands.
It's believed the Newport based steel group have always been confident in their "robust model", regardless of whether the UK voted in or out.
They also say there is now a "stronger case" for a strong, independent, UK owned steel business, following Thursday's vote.
However, Labour MP for Aberavon, Stephen Kinnock, has said the result left "serious concerns" over the future of the steel industry and could affect potential bidders coming forward.
I'm deeply concerned about this result about the future of the steel industry. Uncertainty is the enemy of business and we're looking at an industry which is already battling for survival hanging by a thread in many ways. I'm terribly worried that this vote could be the one that cuts that thread we must now hear from the bidders whether they're staying in and there's rumours that they're not going to be.
Aberavon MP Stephen Kinnock has said he believes Labour leader Jeremy Corbyn should resign in the wake of the Brexit vote.
It comes after Mr Corbyn sacked Hilary Benn as shadow foreign secretary after reports he was co-ordinating a movement to unseat the party leader.
Jeremy Corbyn said has no intention of stepping down as leader of the Labour party, a spokesman said today.
Mr Kinnock told Sky News' Dermot Murnaghan that the party needs a 'hard-headed negotiator'.
I think that what we need now is a hard-headed negotiator. Jeremy is a man of enormous integrity and decency and he has been very effective as a campaigner on issues that he has got a real interest in campaigning on for many, many years.
The job description has changed, these Brexit negotiations are going to dominate British politics for the next three, five, ten years and we need a Leader of the Opposition who really understands that in terms of how the EU is going to work and also ensuring that we’ve got a co-ordinated approach
He added that the job to lead the opposition party following the EU referendum has 'changed completely'.
"These are extraordinary times, unique and unprecedented and the leader of the Labour party has to reflect that".
Mr Kinnock also added he did not consider himself as a candidate for the role.
There are lots of very, very talented people in very senior positions. I’ve only been an MP for one year, the key thing now is to look at what the candidates have got to say, set their stall out and what I think is very important is that they frame that in the context of Brexit."
The First Minister Carwyn Jones is under fire after claiming that the Tata Steel management buy-out team "has not yet raised the money".Read the full story ›
Hundreds of steelworkers are to stage a march in London to keep pressure on the Government to help secure the future of their crisis-hit industry.
Workers from plants across the country will gather on May 25 before walking past Downing Street and Parliament.
Those taking part work for several companies, including Tata, which is selling its loss-making UK assets, including the huge plant at Port Talbot in south Wales.
The steelworkers will demand that the Government works to ensure a responsible sale of Tata Steel and deliver a proper industrial strategy to support the entire steel sector throughout the current crisis.
For months, the Save Our Steel campaign has engaged hundreds of thousands of people across the UK.
This march will bring steelworkers to London to focus all our attention on delivering a clear message to government: save our jobs, support our communities and deliver the fantastic future for British steel making we know it can have.
Liberty House has confirmed it will put in a formal bid to buy Tata Steel's UK assets.Read the full story ›
First Minister Carwyn Jones is expected to call on the Prime Minister to take Welsh plants into 'public ownership', until a buyer is found.Read the full story ›
A meeting has been held at the Tata steel plant in Port Talbot to discuss yesterday's announcement that 750 jobs are to go at the site.Read the full story ›
Unions are temporarily suspending industrial action, after securing an offer from Tata Steel that means the pension scheme would stay open.Read the full story ›