The Hellenic League of Human Rights says the police shooting last month has "highlighted a number of long-standing serious issues".
ADVERTISEMENTHuman rights activists have accused Greek police of racism following the death of a young Roma man.
Officers used "disproportionate armed violence" when they fatally shot 18-year-old Nikos Sampanis last month, the Hellenic League of Human Rights (ElEDA) has said.
The organisation also accused police of "possible racist motives" based on Sampanis' ethnicity.
The 18-year-old was killed by officers on 23 October while riding in a stolen car near Athens.
The fatal shooting took place in Perama, a working-class district of the Greek capital near to where a large Roma community lives.
The ElEDA has said that Sampanis was unarmed when he was killed and that his death has raised "our deepest concern".
The incident has also sparked violent protests in Greece, with objects thrown at police and several shop windows damaged.
How was Nikos Sampanis killed?
According to a statement, officers were alerted to a possible stolen vehicle on the evening of October 22.
"The vehicle, in which three people were riding, had a broken porthole, which is the reason why it was considered suspicious," Hellenic police said.
Officers say the stolen vehicle sped off as they approached, leading to a high-speed chase. After the car was stopped by a bus, police said the occupants tried to reverse away dangerously.
Police say that "seven" officers were wounded after the stolen car "rammed five motorcycles".
"Police officers then used their guns to try and immobilise the vehicle," the statement added.
At least 20 bullets were fired at the car, fatally injuring one person -- later identified as Sampanis -- and wounding another.
Seven police officers have been arrested following the incident and charged with intentional homicide.
Another 20-year-old Roma man and a 14-year-old boy -- who were in the car -- have also been charged with attempted murder of the police officers.
"Excessive and disproportionate violence"
The ElEDA says the police shooting has "highlighted a number of long-standing serious issues".
"The use of armed force by the police against unarmed citizens requires specific and thorough justification, especially when it appears to be particularly excessive and has led to the loss of life of an 18-year-old citizen and injury to a minor," the group said in a statement.
They have accused police of acting like "a film scene" and continuously firing their weapons into the vehicle.
ADVERTISEMENT"Only in this case the incident was real and with tragic consequences," the organisation added.
The ElEDA has called on Greece to investigate whether any "racist motives" led the police officers to use "excessive and disproportionate violence".
"Any allegations of operational failures ... cannot legitimise the use of armed violence against unarmed civilians."
"The incident has also highlighted the wave of racism and anti-Gypsyism that has been brewing in part of Greek society, for which we express our disgust."
The decision to release the seven police officers after they were charged has also been condemned.
ADVERTISEMENTOn Monday, Greece's Ministry of Civil Protection acknowledged a "lack of coordination" within the police during the chase and announced reforms to "improve" the country's security services.