The U.S. government has called on the state of Texas to stay the execution of a Mexican national, saying he was not told at the appropriate time of his right to consular assistance from Mexican authorities.

State Department spokeswoman Victoria Nuland told reporters Tuesday that the federal government filed a brief with the U.S. Supreme Court last Friday in the case of 38-year-old Humberto Leal Garcia.

Nuland said the brief was filed to take into account the fact that Leal Garcia was not afforded a visit by Mexican consular officials at an appropriate moment in the trial proceedings. Leal Garcia is scheduled to be executed this Thursday for the rape and murder of a 16-year-old girl.

The Inter-American Commission on Human Rights has called for a stay of execution until a process can be established to arrange for a review of the case. The commission is an autonomous body of the Organization of American States.

Additionally, the Office of the United Nations High Commissioner for Human Rights has urged Texas Governor Rick Perry to commute Leal Garcia's death sentence. A spokesperson has said the case raises particular concerns, as Leal Garcia was not granted consular access, which, as a foreign national, is his right under the Vienna Convention on Consular Relations.

Two years ago, the International Court of Justice, the U.N.'s highest court, ruled the United States violated the court's order in 2008 when authorities in Texas executed another Mexican national convicted of rape and murder.

The court said in a unanimous ruling that U.S. authorities should have reviewed the case of Jose Medellin, who was not granted consular access during his trial for the 1993 rape and murder of two girls. Texas authorities said Medellin's arrest, trial and sentencing complied with state, national and international laws, and there was no reason to stop the execution.

The U.N. court also said the United States was obligated to abide by the court's 2004 order to review the cases of about 50 other Mexican nationals sentenced to death and determine whether the lack of access to Mexican diplomats affected their cases.

Under the 1963 Vienna Convention, foreign nationals have the right to speak with their country's consulate after their arrests.