There are delays of up to 15 minutes both directions along the A27 Lewes Road near Selmeston.
Eastbound traffic stretches back to the Lacys Hill junction and westbound approximately halfway towards Drusilla’s Roundabout.
It is unclear whether the traffic is related to the ongoing roadworks at the roundabout due to a collapsed manhole cover.
Sussex Police said the collapsed cover is being dealt with by the Highways Agency, which has been approached for comment.
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