A mobile crane fire closed the M25 carriageway in the clockwise direction this morning.
At 9.15am one lane remained closed at the scene between junction 9, at Leatherhead, and junction 10, at Wisley.
But the Highways Agency said drivers are still experiencing delays of about 90 minutes after the incident involving a "heavy goods vehicle".
A Leatherhead fire station spokesman said five pumps and three water carriers were called to a "crane fire" at about 6.30am.
About an hour ago, Surrey Fire and Rescue Tweeted: "We currently have several appliances dealing with a mobile crane fire on the M25 J 8-9."
A Highways Agency spokesman said: "We sent out some traffic officers. Initially the whole carriageway was shut. Now we are just down to one lane closed at quarter past nine."