At least 39 migrants were declared dead Tuesday after a fire was started overnight at a detention facility in Ciudad Juárez, close to the U.S.-Mexico border.
Mexico's National Institute of Migration said in a statement that the detention center held 68 men from Central and South America.
"The National Institute of Migration strongly rejects the acts that led to this tragedy," the agency said, without elaborating.
In an address on Tuesday, Mexican President Andrés Manuel López Obrador said the fire was sparked by migrants in protest of their looming deportation.
"They never imagined that this would cause this terrible misfortune," said López Obrador, who noted that most of those killed in the fire were from Central America and some were from Venezuela.
Photos taken at the detention center in the wake of the deadly fire showed emergency workers on the scene and numerous bodies covered by sheets. Dozens who were injured in the fire are reportedly in serious condition.
The disaster is likely to intensify criticism of the immigration policies of the U.S. and Mexico, both of which have been accused of systematically violating the rights of asylum seekers.
The Associated Press noted that "in recent years, as Mexico has stepped up efforts to stem the flow migration to the U.S. border under pressure from the American government, its National Immigration Institute has struggled with overcrowding in its facilities."
Kerri Talbot, deputy director at the Immigration Hub, argued Tuesday that "the U.S. bears responsibility for pushing these migrants back into Mexico to face unsafe conditions"—a reference to the Trump-era "Remain in Mexico" policy.
In December, a Trump-appointed federal judge blocked President Joe Biden's attempt to end the policy, which rights groups say is illegal.
Meanwhile, Biden has been under heavy criticism from advocates for his asylum proposals.
On Monday, the United Nations High Commissioner for Refugees urged the Biden administration to rescind its proposed anti-asylum rule, which critics have compared Trump's "transit ban" that denied asylum to anyone who had traveled to the United States through a third country.
Key portions of the Biden proposal, said the agency, "are incompatible with principles of international refugee law."
