There are delays of at least 30 minutes on the M1 according to the Highways Agency due to the fire.
Other traffic services and road users are reporting 90 minute delays.
The lorry fire is now out and the motorway has reopened, but there are long delays.
The latest update states: "The fire on #M1 southbound has been put out by @WYFRS . The northbound M1 has been full reopened and the southbound exit slip and link to the tunnel are also open, the closure remains between the slip roads and will remain as we assess the damage to the carriageway."
Drivers are being advised to use the A1M for the south instead.
The incident has happened on the M1 at Junction 42 southbound.