Suspects detained in the disappearances and alleged slaughter of 43 students in Mexico claim they were tortured by authorities, allegations that could harm their trial, human rights experts said Monday.

The envoys of the Inter-American Commission on Human Rights who are in Mexico to conduct an independent investigation said they interviewed 16 of the more than 100 suspects arrested in the case.

Of the 16 suspects, "a relatively large group" claimed they were mistreated or tortured following their arrests, Spanish psychologist and commission expert Carlos Beristain told reporters.

Around 10 official complaints have been lodged with Mexico's National Human Rights Commission, he said.

Beristain said the allegations must be thoroughly reviewed because, if the rights to suspects were not respected, "it would be very negative for the process and it would have legal consequences."

The regional commission launched its own investigation in March following an agreement between the government and parents of the missing students, who reject the authorities' conclusions in the case.

Prosecutors say police in the southern Guerrero state town of Iguala detained the students in September and handed them over to the Guerreros Unidos drug gang, which killed them and incinerated their bodies.

Relatives of the missing students and rights groups have voiced doubts about the official conclusions because they rely on witness accounts. Only one of the 43 missing students has been identified among a set of charred remains found in a landfill and a river.

More than 100 people have been detained, including more than 60 officers from Iguala and the neighboring town of Cocula as well as around 40 suspected gang members.

Last year, a UN expert on torture issued a report saying that torture was a "generalized" practice among authorities in Mexico to extract confessions, a statement that angered the Mexican government.

The Inter-American commission's experts will issue their final conclusions in September, on the anniversary of a case that has sparked protests against President Enrique Pena Nieto.