VIENNA (Reuters) - Forty-one people were hurt - five of them seriously - when two crowded commuter trains crashed head-on in Vienna during the morning rush hour on Monday, authorities said.

The driver of one train and another person remained in critical condition after the mishap, the emergency services in the Austrian capital said.

Operations on the line had been switched to manual following a technical defect with a shunting switch, and a spokeswoman for Austrian railways said human error had not been ruled out as a possible cause of the crash.

"A train got permission to travel when it should not have," she said.

(Reporting by Michael Shields; Editing by Jon Boyle)