'Texas is at the heart of that scandal,' the organisation continued, pointing to the fact that Texas now accounts for 28 of the 58 executions carried out in the USA this year, and 227 of the 656 since the USA resumed judicial killing in 1977.

Brian Roberson and Oliver Cruz were killed by lethal injection within an hour of each other despite serious concerns relating to racial discrimination and mental impairment, two issues that mark many capital cases in the USA.

'US contempt for international standards of justice and decency has once again been on display for the world to see,' Amnesty International said.

The organisation also refutes Governor George W. Bush's reported contention that Texas does not execute the mentally retarded, citing the examples of Terry Washington and Charles Boyd - put to death in 1997 and 1999 - two of the 140 men and Women's rights's rightss rights's rights's rights's rights executed since Governor Bush took office in January 1995.

'The flawed nature of Texas justice was further exposed in the cases of Washington and Boyd as the juries that sentenced them to death were never told of the two men's mental impairment,' Amnesty International said.

Governor Bush did not support a bill to ban the execution of the mentally retarded which failed to pass the Texas legislature in 1999. He also vetoed a bill in 1999 which sought to raise the standard of legal representation for low-income defendants.

Background Brian Roberson, black, was sentenced to death for the 1986 killing of an elderly white couple in Dallas County. The prosecutor at his trial systematically removed African Americans from the jury pool, indicating that they were not educated enough to sit on a jury. The prosecutor had been trained at a time when such training in Dallas County routinely used a manual encouraging new prosecutors to remove 'minority races', 'Jews', and people with 'physical afflictions' during jury selection because they 'almost always empathize with the defendant'. A 1986 study found that in the 15 capital murder cases tried in the county between 1980 and 1986, 91 per cent of African American jurors were removed.

At the trial of Oliver Cruz, a Latino accused of the rape and murder of Kelly Donovan, white, the prosecutor argued for execution on the grounds that Cruz's learning disability made him more of a threat to society. International standards oppose the death penalty for the mentally impaired. In yet another blatant example of the lottery of US capital justice, Cruz's white co-defendant, charged with the same murder, received a prison term in exchange for testimony against Cruz.

Studies have repeatedly shown that the US capital justice system places a higher value on white life. Over 80 per cent of the more than 650 people executed in the USA since 1977 were convicted of crimes involving white victims.