Texas was preparing to execute a 33-year-old Mexican man on Tuesday, defying a ruling by an international court, orders from US President George W Bush and demands from the Organization of American States, the US secretary of state and the US attorney general.

The case, which has become a cause celebre among death penalty opponents, involves Jose Ernesto Medellin Rojas, one of six gang members convicted for the 1993 hour-long rape and brutal murder of two Houston girls, age 14 and 16, as part of a gang initiation ceremony.

Since 1997, Medellin's lawyers and Mexico have been challenging Medellin's death penalty conviction because he is a Mexican citizen and Mexican officials had not been informed of his need for legal help during the trial.

Under the Vienna Convention of Consular Relations, arrested suspects from foreign countries are supposed to have access to their own consulates to seek legal assistance.

In 2004, the International Court of Justice (ICJ) agreed with Mexico and ordered Medellin's case and those of another 50 Mexicans on death row in the US to be reviewed. It followed up last month with an explicit order on the case of Medellin and four other Mexicans on death row in Texas.

Bush, the one-time governor of Texas, tried to carry out the 2004 ICJ decision by taking the unusual step in 2005 of ordering the state of Texas to reopen Medellin's case.

Texas appealed the order to the US Supreme Court, which ruled in March 2008 that the ICJ ruling was binding on the US but that the president had no authority to intervene in state judicial affairs, under a long-standing division of power in the federalist system.

Texas has insisted it will bow only to the US Supreme Court, and not to any international court. Governor Rick Perry, who could stay the execution, has let it be known he's 'not feeling any pressure on this,' a spokeswoman was quoted as saying by the Houston Chronicle.

On Friday, the Texas Court of Criminal Appeals removed the last barrier to Medellin's execution, denying a petition by Medellin's lawyers to stay the execution.

One of the judges who agreed with the majority opinion, Cathy Cochran, wrote that 'no matter how long the courts of this state, the nation or any other nation review, re-review and re-review once again, the disgusting facts of this crime and these perpetrators, the result (death penalty) should be the same,' the Chronicle reported.

The horrific details of the case are these: Jennifer Ertman, 14, and Elizabeth Pena, 16, took a short cut across a park at a late hour in June 1993 and happened upon the gang of six teenage boys, who grabbed and raped them for an hour, evidence showed.

The boys then strangled them with a belt and a shoelace and stomped on their throats. After a four-day frantic search that engaged the entire city of Houston, their bodies were found with the help of a gang member's brother.

Medellin had bragged to his friends that the victims were virgins, Judge Cochran wrote, noting that in his confession, Medellin had 'displayed a callous, cruel and cavalier attitude toward the two girls.'

Five of the gang members were sentenced to death. One has been executed, and a second is awaiting an execution date. Two others had their death sentences commuted to life in prison because they were minors at the time of the crime. The sixth, Medellin's brother, only 14 at the time, is serving a 40-year sentence.

Groups opposed to the death penalty issued another round of protests against Medellin's execution on Monday.

David Fathi of Human Rights Watch in Washington warned that Medellin's execution in violation of an international court order 'will place Americans abroad at risk.'

'If the US disregards its legal obligations in this case, it will be hard pressed to argue that other countries should respect the rights of US citizens under arrest,' he said.

In its March ruling, the US Supreme Court ruled that the ICJ's judgement was legally binding on the US, but that Congress would have to act to make the judgement enforceable. Such a bill is pending in Congress.

Medellin, in a blog posted on the Canadian Coalition Against the Death Penalty, described how he worked out in jail to keep his sanity, and, until his TV was taken away on death row, enjoyed watching sports, particularly women's sports.

'Love that sport bra,' he wrote about women's soccer and tennis.

'I don't want sympathy or pity, I'd rather have your anger. Don't feel sorry for me. I'm where I'm at because I made an adolescent choice. Thats (sic) it!,' he wrote.