The M5 southbound is currently closed between J1 and J2 between West Bromwich and Oldbury after two lorries crashed this morning.
Diversions are in place but the closure has led to delays throughout the area as the crash happened just before 7am.
A Highways Agency spokesman said: "This is due to a serious incident involving a collision and associated extensive diesel spillage.
"Traffic is being diverted following the 'hollow yellow triangle' diversion route symbol, utilising the A457 (Oldbury Road) and the A4034 (Churchbridge)."
The spokesman added: "There are severe delays on the M6 southbound from J11, as well as on both the M5 southbound from the M6, and the M5 northbound from J4 near Frankley services."