Argentine club Boca Juniors have been thrown out of the Libertadores Cup after players from rivals River Plate were attacked with what appeared to be pepper spray, the South American Football Confederation (CONMEBOL) said on Saturday.

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CONMEBOL also hit Boca with a $200,000 fine and ordered it to play four home games behind closed doors and another four away games without its fans.

Four River Plate players were taken to hospital after they were sprayed with an irritant by fans of their bitter rivals on Thursday, causing their Libertadores Cup derby to be abandoned at halftime.

The last 16 second leg tie between the Buenos Aires clubs at Boca's Bombonera stadium was deadlocked at 0-0 when the incident occurred in the tunnel as the players came out for the second half.

Football in Argentina has been blighted in recent years by violence. In December, Franco Nieto died after being struck in the head following a match between regional club Tiro Federal and Chacarita Juniors.