The wife of the ex-mayor of Iguala, the Mexican city where 43 college students went missing in September and are feared dead, has been jailed indefinitely on suspicions of masterminding the abductions that rocked the country, prosecutors have said.

Maria de los Angeles Pineda, who had been held under provisional arrest, has been transferred to a high security prison in the western state of Nayarit from the capital Mexico City.

On Monday, a judge issued a warrant for her pretrial detention "for her likely role in committing organised crime ... and operations with funds of illicit origin," said Tomas Zeron, who leads the criminal investigation unit of the prosecutor's office.

Pineda and her husband Jose Luis Abarca, Iguala's former mayor, have been named by prosecutors as the "probable masterminds" of the kidnappings allegedly carried out to prevent opposition demonstrations.

The students went missing September 26, in an apparent massacre by a police-backed gang that sparked nationwide protests and caused a crisis for President Enrique Pena Nieto.

Confessions made during the investigation have indicated that Abarca ordered police to crack down on the students to stop them from protesting at a public event his wife was to lead.

Authorities say the aspiring teachers vanished after gang-linked police attacked their buses in the city of Iguala, allegedly under orders from the mayor and his wife in a night of terror that left six other people dead.

The police then delivered the young men to members of the Guerreros Unidos drug gang, who told investigators they took them in two trucks to a landfill, killed them, burned their bodies and dumped them in a river.

For now, only one of the students has been positively identified from charred remains, which leaves little hope of finding the 42 others.

On Christmas Eve, the students' parents held a protest under heavy rain in front of the Los Pinos presidential palace.