Egypt's prosecution ordered on Tuesday DNA tests to identify the bodies of the seven Mexican tourists and four Egyptian guides who were among 12 killed by security forces in the Western Desert after being mistaken for terrorists.
The prosecution said it was difficult to identify the bodies as they did not have passports or identification on them.
Ten people were also injured in the attack.
Mexico's foreign minister flew to Cairo on Monday.
"We face a terrible loss of human life and an unjustified attack which obligates us to prioritise the protection of our citizens," foreign minister Claudia Ruiz Massieu told reporters at Mexico City's international airport.
Egyptian prosecutors and judicial sources said seven of those killed in the incident were Mexicans and four Egyptians, and Mexico's president Enrique Pena Nieto confirmed that two Mexicans had died.
The US State Department spokesman John Kirby has said that the US embassy in Cairo is making "appropriate inquiries" with Egyptian police concerning reports that a US citizen was among those wounded in the accident.