The Mexican attorney general’s office made the claim one day after an independent experts’ report said the incident did not happen.
Tomas Zeron, the director of Mexico’s criminal investigation agency, said that although there may have been errors in the initial investigation, they remain confident in the forensic science and the conclusion, adding that 100 investigators were involved.
Mr Zeron said: “We can’t be wrong.”
The students disappeared on September 26 2014, in the southern state of Guerrero.
Francisco Cox, one of the experts on the independent commission sent by the Inter-American Commission on Human Rights, told Milenio television that it is possible the students were burned elsewhere, but not at the dump.
In response to the report, attorney general Arely Gomez said she would order a new examination of what happened at the dump.
Eber Omar Betanzos Torres, deputy attorney general for human rights, said discussions were under way to select a group of pre-eminent investigators to make a third examination of the site.
He said: “The attorney general’s office has always been interested in meeting the highest international standards...”
The independent experts’ report dismantled the government’s long-held official version and found numerous problems in the investigation. Parents of the students have long refused to accept the government’s version.