The fingerprints and DNA samples of more than 857,000 innocent citizens who have been arrested or charged but never convicted of a criminal offence now face deletion from the national DNA database after a landmark ruling by the European court of human rights in Strasbourg.

In one of their most strongly worded judgments in recent years, the unanimous ruling from the 17 judges, including a British judge, Nicolas Bratza, condemned the "blanket and indiscriminate" nature of the powers given to the police in England, Wales and Northern Ireland to retain the DNA samples and fingerprints of suspects who have been released or cleared.

The judges were highly critical of the fact that the DNA samples could be retained without time limit and regardless of the seriousness of the offence, or the age of the suspect.

The court said there was a particular risk that innocent people would be stigmatised because they were being treated in the same way as convicted criminals. The judges added that the fact DNA profiles could be used to identify family relationships between individuals, meant its indefinite retention also amounted to an interference with their right to respect for their private lives under the human rights convention.

The case provoked an expression of disappointment from the home secretary, Jacqui Smith, and the promise that a working party, including senior police officials, will report back to Strasbourg by next March on how the government will comply with the judgement.