Mexican authorities have found four more secret graves containing charred human remains at a site where officials fear missing students were massacred by gang members and police.
Attorney General Jesus Murillo said the arrest of new suspects led authorities to the new mass graves.
"They were able to take us to a place where we found four mass graves, which these detainees said were also where the remains of the murdered students were deposited," he said.
The students went missing after a protest over job discrimination.
Police allegedly opened fire on their buses as they arrived in the city of Iguala, in the troubled south-western state of Guerrero, on 26 September.
The new find brings to ten the number of graves discovered on the outskirts of Iguala.
Authorities have arrested 22 local police in connection with the disappearance of the 43 students.
Protesters have said responsibility for the apparent massacre lies with the state governor.
Mr Murillo said DNA samples were being taken from their relatives to check against the remains found.
The discovery of mass graves has stoked public anger for justice amid reports that local security officials are suspected of conspiring with gang members to kill the students.
In Guerrero, home to Iguala and Acapulco, protesting teachers set up camp outside government headquarters in the state capital to call for the resignation of Governor Angel Aguirre Rivero and for Iguala's fugitive mayor Jose Luis Abarca to face justice.
"We will keep up the fight until Aguirre Rivero is fired, Abarca from Iguala faces a political trial and that the 43 students from Normal (school) in Ayotzinapa appear. We will keep on fighting, they will not repress us," said one protester.
Mexican President Enrique Pena Nieto has called for a thorough investigation to apprehend those behind the killings.
"This is an act that cannot go unpunished. We need to go deep to reach those responsible, those who by negligence or action or who covered up so that this could happen in Iguala," he said.
The apparent massacre has created a major headache for Mr Pena Nieto, who took office two years ago pledging to end a wave of gang-related violence that has killed around 100,000 people since the start of 2007.
