UPDATE 19.24
A Gwent Police spokesman said: "We had reports of a Road Traffic Collision 15 minutes ago.
"There are two cars on the hard shoulder.
"Highway agency officers, one of our traffic cars and an ambulance are in attendance.
"It looks like a blowout, but we're not sure."
The spokesman said that one lane while remain closed while they recover the vechicles.
He said that, if there are any injuries, they'll be minor.
19.15
TWO cars have been involved in a crash on the M4.
There's very slow traffic westbound at J29.
The M4 exit slip road to the A48 is partially blocked.
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