Media playback is unsupported on your device Media caption Jason Clark, from the Texas Department of Criminal Justice: ''He was pronounced deceased...17 minutes after the lethal dose began''

The US state of Texas has executed a Mexican for murder, despite objections from the US and Mexican governments.

Mexico argued the execution of Edgar Tamayo, 46, would violate international law, because he was not told of his right to seek legal assistance from the Mexican consulate when he was arrested.

US Secretary of State John Kerry made the rare move of asking Texas to delay the execution.

But it went ahead, after a last-minute appeal to the US Supreme Court failed.

The execution - initially scheduled for 18:00 local time on Wednesday (midnight GMT on Thursday) - was delayed as prison officials awaited word from the US Supreme Court over an appeal to keep Tamayo alive.

The Supreme Court subsequently announced it had denied a stay of execution.

Tamayo declined to make a final statement before he was injected with pentobarbital at Huntsville prison. He was pronounced dead 17 minutes later at 21:32 (03:32 GMT Thursday).

The execution was witnessed by the mother and four other relatives of his victim.

'The ultimate penalty'

Image copyright Reuters Image caption Tamayo was living in the US illegally before the crime

In January 1994, Tamayo shot and killed police officer Guy Gaddis, 24, as he was being arrested for robbery. He was in the US illegally.

Gaddis, who had been on the Houston police force for two years, was driving Tamayo and another man when he was shot three times in the head and neck with a pistol Tamayo had concealed in his trousers.

Texas executes more offenders than any other US state. Sixteen people were put to death last year in Texas, compared to seven in Florida, the state with the second-highest execution count.

Tamayo's lawyers and Mexican officials said he was protected under a provision of the 1963 Vienna Convention on Consular Relations that allows arrested citizens of foreign countries to receive legal assistance from their consulates.

But Tamayo was not notified of his right to seek consular assistance.

His lawyers argued such assistance could have uncovered evidence to contest the capital murder charge or to keep Tamayo off death row.

Texas officials have maintained their procedures met US Supreme Court guidance.

"It doesn't matter where you're from," said Lucy Nashed, a spokeswoman for Governor Rick Perry. "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."

But Mr Kerry had asked Texas officials to delay the execution by lethal injection in order to review whether the lack of access prejudiced the outcome of the case.

In a letter to state officials, America's highest ranking diplomat, a former prosecutor, said he had "no reason to doubt the facts of Mr Tamayo's conviction" but was concerned about how the case could affect US-Mexico relations and the way Americans are treated overseas.

On Tuesday, state department spokeswoman Marie Harf said: "If we our self don't uphold those obligations, it will make it much harder for us to ask other countries to do so."

Former Texas Governor Mark White had also called for a review, writing in the Austin American-Statesman newspaper he believed in capital punishment but "this case is not about whether we support or oppose the death penalty. It's about fairness and having the courts hear all the key facts."

The Mexican government has warned Texas' failure to review Tamayo's case and reconsider his sentence would be "a clear violation by the United States of its international obligations".

Image copyright Getty Images Image caption "This is a process issue," Mr Kerry said in a letter. "I am raising because it could impact the way American citizens are treated in other countries."

He was among the four dozen Mexican nationals awaiting execution in the US in 2004 when the International Court of Justice in The Hague, Netherlands, ruled they had not been advised properly of their consular rights.

Former President George W Bush ordered Texas and other states to review the cases, but the US Supreme Court ruled in favour of the state in 2008, saying the president could not effectively enforce The Hague's ruling, leaving it to Congress to pass legislation.

Two other men in The Hague case have already been executed despite Mexico's objections.