FORENSIC experts have combed a gully in southern Mexico for the remains of 43 missing students, as frustration mounted among relatives over the lack of answers more than a month into the investigation.

Workers in protective gear focused on a 25-by-25ft-square area below the ridge of the municipal dump in Cocula, a town in Guerrero state where police have been arrested and linked to the September disappearances.

But the authorities have so far not said how many bodies have been found or what condition they are in.

Parents of the students say they were not even notified of the latest remains, which we discovered on Monday after information was provided by four new detainees in the case.

Mario Cesar Gonzalez, father of missing Cesar Manuel Gonzalez, said: "We're angry and very tired. We have an overwhelming sense of helplessness."

Attorney General Jesus Murillo Karam said: "I prefer taking more time to find the truth than rushing to put out a guess, imagination or invention."