A section of motorway was closed after a lorry left a “significant” oil spill across the carriageway.
The southbound M61 in Greater Manchester was shut between Junction 4 near Bolton and Junction 2 while the road was cleared after the spill at about 08:20 BST.
National Highways said the HGV spilled oil across two lanes, stretching for a distance of about 2km (1.2 mile).
Drivers were urged to allow extra time for journeys with the clean-up expected to take several hours and the closure still remaining in place some time after 14:00 BST.
Traffic officers were at the scene assisting with traffic management, while two road sweepers and a sander were sent to help clear the oil.
Drivers travelling south were being diverted at Junction 4 along a signposted route.