13:00 A Welsh Government spokesperson said,
"Our team has worked throughout the night to clear the debris and make the site safe for our engineers to carry out a full structural, technical and safety assessment of the tunnel. Once these assessments are completed we will know the extent of the damage and the work required to bring the tunnel back into use.
"Until this work is completed, which we envisage will take a couple of days, the westbound tunnel will remain closed. We appreciate your patience and understanding while we carry out this essential work.
"Traffic Wales have created a new webpage to update the travelling public on developments at the site which will go live shortly at www.traffic-wales.com .
"We are more aware than most of the strategic and economic importance of the M4 to Wales. In 2009 we announced plans to address issues around capacity, safety and resilience along the M4 corridor that were both deliverable and affordable, and as an alternative to the relief road scheme. These measures included improvements to motorway junctions, train stations and park and ride facilities throughout south east Wales.
"Last year we announced the purchase of the Queensway Road, which passes through the Llanwern steel works, which we plan to upgrade to a dual carriageway and which will provide an alternative route through Newport and improve the resilience of the network."
17:00 A Welsh Government spokesperson said,
“The eastbound tunnel at Brynglas has now reopened. A contra flow system is in operation with traffic moving in both directions. All junctions have now also fully reopened.
“Our multiagency team are working around the clock to reopen the westbound tunnel. It is clear that there remains considerable work to clear debris and conclude the structural assessment to ensure the tunnel is safe for use.
"We will continue to provide regular updates and work as quickly as possible to resolve the situation. We would appreciate your continued patience and understanding at this time."
15:45 A Welsh Government spokesperson said,
“South Wales Fire and Rescue have now confirmed that the fire is completely extinguished and they will soon be leaving the scene. Structural engineers will now enter the westbound tunnel to carry out an assessment of the damage caused.
“Traffic congestion is now obviously a major concern and we would urge any motorists planning on using the M4 in south east Wales to make alternative arrangements.
“Whilst we are doing everything we can to inform motorists in real time, with live traffic updates and wide area signing, we would ask for your cooperation and understanding as we attempt to relieve pressures on the network and reopen the tunnels.”
11.25 A Welsh Government spokesperson said,
"The Brynglas tunnels on the M4 in south Wales were closed in both directions at approximately 0835 this morning due to a vehicle fire.
“Due to the severity of the fire, emergency services will require that the tunnels remain closed until a full and thorough investigation and structural examination is completed.
“While these delays will undoubtedly cause inconvenience to motorists, the safety of road users and emergency staff must remain paramount.
“Diversionary routes have been put in place via the south of Newport on the A48 Southern Distributor Road.
“Please check http://www.traffic-wales.com/ and local radio for traffic updates.”