Taking into account the worsening condition of Roma communities across European countries, Amnesty International warned that the governments are not doing enough to improve the precarious living conditions and protect them from hate crimes, sometimes perpetrated by police.
In a report coinciding with International Roma Day, the rights group said many of the 10 to 12 million Roma living in Europe face "the daily threat of forced eviction, police harassment and violent attacks".
"The conditions in which many Roma are forced to live are a damning indictment of years of official neglect and discrimination," the group said.
The Roma, a traditionally nomadic people whose ancestors left India centuries ago, have long suffered from discrimination.
They were killed in their hundreds of thousands by the Nazis during World War II, alongside Jews and homosexuals.
Discrimination continues today as some countries blame Roma for a rise in petty crime.
In Greece, for instance, Amnesty blamed law enforcement for failing to intervene to stop racially motivated attacks, discouraging victims from filing complaints and failing to probe or effectively investigate complaints that are lodged.
"In many cases police officers themselves are perpetrators of hate crime," it said.
Greece is home to between 250,000 and 350,000 Roma, the rights group said.
According to official statistics, police conducted some 1,130 operations in Roma settlements across the country during the first nine months of last year.
Officers checked more than 52,400 people during those operations and more than 19,000 were taken to police stations. Of those, 1,305 were arrested.
"Following its visit to Greece, the UN Working Group on Arbitrary Detention expressed its concern over the rounding up of members of the Romani community who were released soon after without charge," the report said.
- 'Pandering to prejudices' -
France, meanwhile, pursues a controversial policy of forcibly evicting Roma from their camps, often paying them to return to their countries of origin, mainly Romania and Bulgaria.
Many of France's 20,000 Roma live in extreme poverty in makeshift settlements with little or no access to basic services, such as water and sanitation, and at constant risk of forced evictions, Amnesty said.
The report cited several examples of alleged police brutality against Roma, including spraying tear gas inside tents where children were sleeping and beating up one man in the southern city of Marseille.
It also pointed to comments made in September by then interior minister Manuel Valls, now the prime minister, in which he said most of the Roma in France had no intention of integrating and should be sent back to their countries of origin.
"More often than not, (national authorities) have pandered to the prejudices fuelling anti-Roma violence by branding Roma as anti-social and unwelcome," Amnesty said.
"For its part, the European Union has been reluctant to challenge member states on the systemic discrimination of Roma that is all too evident."
The report urged national governments and the European Union to commit to eradicating anti-Roma violence, by for instance ensuring that authorities investigate crimes against Roma and that police officers who are likely to come into contact with victims receive adequate training; and by ending forced evictions.