By Pietro Lombardi and Corina Pons MADRID, Jan 23 (Reuters) - A series of accidents in one week on Spain's railways, including one of the deadliest in Europe, has left the country reeling and put the spotlight on whether investment to maintain the network is keeping pace with surging passenger demand.

Distressing accounts from survivors and rescuers were emerging after the collision in Adamuz, a small town near the city of Córdoba, and Spain's transport minister warned that the death toll was "not final" in the crash, the deadliest in Spain since at least 2013.

MADRID -- A high-speed train derailed in southern Spain on Sunday, jumping onto the track in the opposite direction and hitting an oncoming train in an accident that authorities estimate left more than 20 people dead and dozens injured.