The controversial execution of a Mexican man convicted of murder in Texas was briefly delayed as the US Supreme Court considered a last-minute appeal. Edgar Tamayo Arias, 46, had been scheduled to be put to death by lethal injection at 6:00 pm (0001 GMT Thursday) for the 1994 murder of a policeman in Houston. But Texas prison officials told AFP they will give the court until midnight (0600 GMT) to decide if it will issue a temporary reprieve in order to more fully consider the case. Tamayo's case has 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 1963 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. Tamayo spoke very little English at the time of his arrest and he is mentally handicapped, his lawyers say. The attorneys have argued he would never have been sentenced to death if the Mexican government had been made aware of his case and been allowed to assist in his legal representation. "We are continuing to pursue our options for appeal, and vindication of Mr Tamayo's right to review of the consular rights violation in his case," defense attorney Maurie Levin told AFP. Their 11th-hour appeal asks for a stay of execution and a review of the case. 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. "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 has complained bitterly about Tamayo's imminent execution and repeatedly asked for it to be postponed. Secretary of State John Kerry wrote to Texas Governor Rick Perry late last year asking for a stay and emphasizing the importance of the case on a wider diplomatic level. But neither Perry nor the Texas Board of Pardons and Paroles were swayed. And a Texas-based federal judge rejected Tuesday a request for a stay of execution as well as a review of the case. Judge Lee Yeakel ruled that the Texas parole board had "provided Tamayo adequate due process" in accordance with Supreme Court and federal court precedent. The US government has also renewed pressure on Texas to grant a postponement. State Department deputy spokeswoman Marie Harf said Washington was asking for "a delay in execution, until we can see whether denying him this access -- the consular access he's afforded under the Vienna Convention -- prejudiced the outcome. She warned that the case could impact the consular access American citizens can receive overseas when arrested.