MADRID (Reuters) - At least 21 people were killed and 40 were injured when a Spanair passenger jet crashed on takeoff at Madrid airport on Wednesday, a source at the Spanish emergency services said.

Local media reports of the death toll varied widely, with one report suggesting it could be as high as 50, after the MD-82 jet shot off the runway carrying 160 passengers.

Flight JK5022 had been bound for Las Palmas in the Canary Islands. A large cloud of smoke rose above Terminal Four after the crash.

Spanair is a subsidiary of Scandinavian Airlines Systems (SAS).

(Reporting by Emma Pinedo, Jesus Aguado and Robert Hetz; Editing by Angus MacSwan)