People march while holding images of the missing students in Mexico City. Picture: Marco Ugarte/AP.

Mexico City - Hundreds of Mexicans marched on Friday to demand more action to clarify the fate of over 40,000 people who remain missing in the country.

"We want them alive," protesters chanted in Mexico City, where they had gathered to mark the International Day of the Victims of Enforced Disappearances.

In front of the government building, an artistic installation featured the number 40,000, white and red flowers, pictures of those missing and black figures on which people could write messages.

Most of the victims had disappeared since 2006.

The under-secretary for human rights, Alejandro Encinas, said the search for them is "the priority" of President Andres Manuel Lopez Obrador's government. Lopez Obrador took office on December 1.

Karla Quintana from the National Search Commission said 3,024 mass graves and more than 4,800 bodies have been found since 2006.

Many of the bodies have still not been identified.

The government announced that it will allow the UN Committee on Enforced Disappearances to investigate the situation in Mexico.

The problem of the disappearances had long been downplayed, leaving many families to search for the victims by themselves, without help from the authorities, Encinas said.

The disappearances are attributed mainly to organized crime and to security forces.

DPA