The M4 is closed in both directions between Junction 24 and Junction 28 following a serious crash.
Initial traffic reports suggest that two motorcycles were involved and that the crash happened at around 6pm on the eastbound carriageway.
Chief Inspector Michelle Booth, Gwent Police, said: “Gwent Police are at the scene of a serious incident on the M4.
“The M4 remains closed at this time in both directions between junctions 24 and 28 whilst Gwent Police investigate. Diversions are in place.”
Police have said there is no further information at this time.
UPDATE: Man killed in M4 crash on Christmas Day