Mexico's government on Wednesday pressed the US to co-operate identifying white supremacists who pose a threat to its citizens after a weekend shooting in El Paso, Texas, killed eight Mexicans.
Twenty-two people lost their lives in the Walmart shop massacre, which Mexico has vowed to investigate as an act of terrorism.
It said it might also request that the perpetrator be extradited to Mexico for trial.
In a diplomatic note published by its Foreign Ministry, the Mexican government said it wanted US authorities to share all information on the El Paso case to "determine if there are other individuals and organisations of 'white supremacy' seeking to put our community in danger in the United States".
Saturday's attack caused widespread concern in Mexico at a time of recurring diplomatic tension over trade and immigration with the administration of US President Donald Trump.
Mr Trump, whose insults against migrants have angered many Mexicans, on Wednesday visited hospitals where victims of the shooting were treated in El Paso.
The diplomatic note, which was addressed to the American embassy in Mexico, urged the US to "make happen" the words Mr Trump used on Monday when he called on Americans to "condemn racism, bigotry and white supremacy".
A four-page statement by the shooter, Patrick Crusius, and posted on 8chan, an online message board often used by extremists, called the El Paso attack "a response to the Hispanic invasion of Texas".
Texas was part of Mexico before it broke away in the 1830s, and later joined the US.
Democratic presidential front-runner Joe Biden on Wednesday accused Mr Trump of fuelling the white supremacy beliefs blamed for the shootings.
"In both clear language and in code, this president has fanned the flames of white supremacy in this nation," Mr Biden, the former vice president, said in a speech in Burlington, Iowa.
Another contender for the Democratic presidential nomination, US Senator Cory Booker, took up the themes of white nationalism and gun violence in a speech at the historically black South Carolina church where white supremacist Dylann Roof shot dead nine people in 2015.
"These acts of hatred do not happen in a vacuum," Mr Booker said at Emanuel African Methodist Episcopal Church in Charleston.
"They are harvested only once they have been planted."
