BEIJING - Service on Beijing's subway line 4 has been back to normal after repairs made necessary by a signal failure earlier Monday morning.

The service gradually resumed from 9:10 am when the subway operator, Beijing MTR corporation Limited, fixed the signal failure, company sources said.

The line suspended operation at around 7 am, delaying journeys for thousands of passengers.

The line, which runs 50 kilometers with 35 stations through Beijing from south to north, is one of the busiest in the capital.