AMFISSA, Greece— Two policemen pleaded innocent Friday at their trial on charges of fatally shooting of a teenager in an incident that provoked nationwide riots and a resurgence in far-left and anarchist attacks in Greece.

Epaminondas Korkoneas is the key defendant, charged with murder for the Dec. 6, 2008, shooting that followed an altercation with youths who taunted the officers and threw plastic bottles at their patrol car. The second defendant, Vassilis Saraliotis, pleaded not guilty to the charge of complicity to murder.

The teen's death — in a part of Athens with cafes frequented by anarchists and students — triggered days of violent rioting that spread to cities and towns throughout Greece. Rioting in Athens again last year, on the anniversary of the shooting, led to more than 130 arrests.

Korkoneas, 39, claims the 15-year-old schoolboy Alexandros Grigoropoulos was killed by a warning shot fired into the air that ricocheted.

"I don't accept liability for anybody's death," he told the Amfissa court. "I would have stepped forward to shield anyone, including these kids."

Co-defendant Saraliotis, 33, said he also was innocent "and will prove it."

"I have nothing to do with my colleague's actions," he told the court.

The dead teenager's mother, Gina Tsalikian, accused Korkoneas of intentionally shooting her son and walking off "as if he had just squashed a cockroach."

The trial is expected to take several weeks, and is being held in Amfissa, some 120 miles (200 kilometers) west of Athens, for security reasons amid fears of more rioting by anarchists. (AP)