Washington: Texas executed a Mexican on Wednesday convicted of killing a policeman, despite a diplomatic outcry and pressure from the US federal government to further review his case.

Edgar Tamayo Arias’s case had sparked widespread protests as he was not advised of his right to receive consular assistance at the time of his arrest — in violation of the Vienna Convention on Consular Relations.

“The Mexican government urges effective action and calls for avoiding other sentences issued in contempt of the International Court of Justice’s ruling in order not to damage the regime of consular assistance and protection agreed between the countries,” a Foreign Ministry statement read.

It said that Tamayo’s remains would be sent to Mexico, in accordance with the family’s wishes.

The inmate’s lawyers had hoped to win a last-minute reprieve from the US Supreme Court after failing to persuade lower courts, only to have their appeal for a stay of execution denied in a matter of hours.

Tamayo, 46, was pronounced dead at 9.32pm (0332 GMT) in the execution chamber of Huntsville prison after declining to make a final statement, spokesman Jason Clark said.

His lawyers said he spoke very little English at the time of his arrest for the 1994 murder of a policeman in Houston and is mentally handicapped.

“If he had had the assistance of the Mexican consulate at the time of trial, Mr Tamayo would never have been sentenced to death,” defence attorneys Sandra Babcock and Maurie Levin said in a statement.

In 2004, the UN’s International Court of Justice ordered the United States to provide judicial review of the convictions and sentences of Tamayo and 50 other Mexican nationals who were denied consular assistance.

Tamayo was the third Mexican national to be executed in Texas without proper judicial review, and a fourth is scheduled to be put to death in April.

“The execution of Mr Tamayo violates the United States’s treaty commitments, threatens the nation’s foreign policy interests and undermines the safety of all Americans abroad,” his lawyers added.

“It is now imperative that Congress promptly act to ensure passage of legislation that will bring the US into compliance with its international legal commitments and provide judicial review to the Mexican nationals who remain on death row in violation of their consular rights.”

The 1963 Vienna Convention treaty, to which 176 nations are party including the United States, sets out how authorities must act when foreign nationals are arrested or detained.

This involves notifying the individuals in question of their right to have their consulate informed of their arrest. They subsequently also have the right to consular assistance.

“There are many other foreign nationals on death row who were denied their consular rights, and some of them may be completely innocent,” Mark Warren of Human Rights Research told AFP.

“The damage to America’s international reputation worsens with each execution, but the solution is simple: just pass a federal law requiring a fair judicial review of these claims.”

Mexico complained bitterly ahead of Tamayo’s execution and repeatedly asked for it to be postponed.

In Tamayo’s native central Mexican state of Morelos, relatives and friends formed a circle and held hands in prayer on Wednesday before the execution. Many broke down in tears upon learning he had been put to death.

Amnesty International condemned his execution and the actions of the state of Texas.

“When Texas authorities took Edgar’s life they defied our nation’s international obligations,” it said in a statement.

Secretary of State John Kerry wrote to Texas Governor Rick Perry late last year asking for a stay of execution until the consular assistance issue was reviewed.

The State Department has repeatedly emphasised the importance of the case on a wider diplomatic level, and warned that it could impact the consular access American citizens can receive overseas when arrested.

But neither Perry nor the Texas Board of Pardons and Paroles were swayed.

“It doesn’t matter where you’re from — if you commit a despicable crime like this in Texas, you are subject to our state laws, including a fair trial by jury and the ultimate penalty,” Perry spokeswoman Lucy Nashed told AFP.

A Texas-based federal judge rejected Tuesday a request for a stay of execution as well as a review of the case, saying the Texas parole board had provided Tamayo “adequate due process.”