Christos Panagopoulos, NET's chairman, said the protesters had violently forced
their way into the studio. "This goes beyond any limit,'' he said.
The protest interrupted coverage of a speech by Costas Karamanlis, the country's prime minister, to parliament.
During his address, Karamanlis said: "Long unresolved problems disappoint young people, the lack of meritocracy, corruption in everyday life, a sense of social injustice.
"The fight against them is hard and constant and we are committed to it."
Violence over the shooting of Alexandros Grigoropoulos continued on Tuesday when about 100 youths attacked a police station in Athens, setting fire to a police bus and four cars belonging to officers.
Students blocked streets in the capital and dozens of teenagers gathered outside Athens' main court complex and a maximum security prison where some threw stones at police.
Protesters have called for riot officers to be pulled off the streets, for police to be disarmed and for the government to revise its economic, social and education policies.
Since the shooting, shops have been looted and cars smashed during protests in many cities around the country.
Greece's national confederation of commerce estimates 565 shops have been damaged in Athens alone, at a cost of $275m.