WASHINGTON (AFP) - The US state of Texas executed a Mexican man convicted of murder on Wednesday despite a diplomatic outcry and pressure from the federal government to further review his case.

Edgar Tamayo Arias, 46, was pronounced dead at 9.32 pm (0332 GMT) in the execution chamber of Huntsville prison, spokesman Jason Clark said.

The prisoner declined to make a final statement.

His 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.

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

"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.

He will be the third Mexican national to be executed in Texas without proper judicial review of the fact that they were denied their right to consular assistance, they noted.

"The execution of Mr Tamayo violates the United States' treaty commitments, threatens the nation's foreign policy interests, and undermines the safety of all Americans abroad," they 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 US, 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.

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