Two lanes have been closed on the M25 after an oil spillage, causing 14 miles of tailbacks.
The spillage happened on a section of the clockwise carriageway between junctions two and three in Dartford, Kent.
Tailbacks stretch as far back as Chelmsford, Essex, (junction 28), and motorists are experiencing three-hour delays, National Highways said.
The agency is advising drivers to avoid the area if possible.
A third lane will be closed overnight as the road is resurfaced.