The family of a Mexican convicted murderer executed in Texas in defiance of the International Court of Justice held onto the hope that the execution would be postponed until the last minute, a cousin of the deceased said on Wednesday.

Texas put to death 33-year-old Jose Ernesto Medellin late on Tuesday, ignoring a last-minute appeal from UN Secretary General Ban Ki-Moon.

Medellin's execution was delayed for more than three hours while the US Supreme Court pondered a last-ditch appeal from his lawyers asking for time so the US Congress and Texas legislature could pass laws to make the state comply with ICJ orders.

"We maintained hope that they would keep delaying the execution until after midnight. We believed they would postpone it," said Reyna Armedariz, Medellin's cousin, sobbing, at the family home on the Mexican border.

Finally, in a 5-4 decision, the Supreme Court majority wrote that the chance for legislative action was "too remote" to justify a stay of execution.

A neighbour called Armedariz's house shortly after 10pm and in tears broke the news of the execution she had received from a brother in Houston.

The ICJ told US authorities in 2004 that Medellin's case and that of dozens of other Mexicans facing execution violated the Vienna Convention because, as foreigners, they were not informed of their right to consular access and assistance during trial.

Texas says its state courts are not bound by the ICJ treaty.

Mexico sent a protest letter to the US State Department after the execution expressing concern "for the precedent it could set for the rights of Mexican nationals that could be detained" in the United States.

Medellin was sentenced to death for the 1993 rape and murder of two girls, aged 14 and 16, in Houston, Texas.

Armedariz said she hoped her cousin's body would now be transferred to the family home in Nuevo Laredo.

"We can't leave him there. They don't want him. They killed him," she said.

AFP