Alternating stop/slow conditions had been in place.

A reduced 60km/h speed limit is in place at the crash site.

Motorists should continue to exercise care in both directions.

For the latest traffic information, download the Live Traffic NSW app, visit www.livetraffic.com or call 132 701.

Hundreds of litres of diesel were spilled on the Mitchell Highway Wednesday morning following a crash.

Emergency services received the call just before 4am after a tipper and dog trailer carrying asphalt "left the road" on May 18.

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A statement from Orange Fire and Rescue said: "The dog trailer separated from the tipper and both fuel tanks were ruptured spilling approximately 400 litres of diesel onto the roadway.

"The spill was contained using absorbent material and the driver was uninjured."

FRNSW responded with two fire trucks from Orange and a hazmat van from Bathurst.

Rural Fire Service, police and Roads and Maritime Services attended.

As of 6am the highway was still blocked in both directions.

Drivers at the scene at around 8am reported major congestion along Amaroo Road and that traffic is being redirected via Peabody Road.

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