Mexico City, Mexico - The two US officials who were killed on Sunday in a car accident in Mexico have been identified as CIA agents in new reports on the murky case.

Three people with knowledge on the matter confirmed to CNN that the two SUPPOSED US embassy workers were actually CIA agents, who had allegedly been collaborating with Mexican officials on expanding drug-fighting operations.

The agents died on Sunday, along with the Director of Chihuahua's State Investigation Agency and another local official, when their vehicle reportedly skidded off the road and plunged into a ravine before exploding.

Mexican President Claudia Sheinbaum on Monday revealed that her government had been "unaware of any direct collaboration between the state of Chihuahua and personnel from the US Embassy in Mexico."

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The issue is politically contentious, as Sheinbaum's government faces pressure not to allow US military and law enforcement personnel to operate in Mexican territory.

"They must have authorization from the federal government for this collaboration."

"We're investigating what these people were doing and what agency they were working for," Sheinbaum said on Tuesday, confirming that a full investigation is underway.