MEXICO CITY (AP) — Mexico's Senate approved a legislation Thursday that would impose long prison sentences for forced disappearances and calls for a national system for searching for missing persons.

The measure passed on 90-3 vote, with three abstentions, and now goes to the lower house for consideration.

Disappearance refers to abductions in which the victims are not found, an issue that has surged to the forefront in Mexico amid a bloody drug conflict and searches by families for missing loved ones. The government's human rights agency says 32,236 people have gone missing across the country over the past two decades.

Kidnapping is already illegal in Mexico. But the legislation defines disappearance as a continuing crime, for which there is no statute of limitations. It would set prison terms of 40 to 60 years for public servants and 25 to 50 years for other people who engage in the crime.

The measure also would establish a responsibility for the government to look for the disappeared, but the details of how such searches would be carried out must still be determined.

Human rights groups praised the vote, saying thousands of families have suffered for years after their relatives were disappeared by drug gangs, police or military units.

Prosecutors say 855 clandestine graves containing 1,548 bodies have been found since 2007. Only about half of those bodies have been identified. Press accounts indicate 1,143 pits had been found nationwide, containing 3,230 bodies.

The families of disappeared people in Mexico have long complained of a lack of information and real investigation into their loved ones' whereabouts. Many of clandestine graves have been found by relatives searching on their own.

Federal and state governments have been slow to establish DNA registers and other databases that might allow the identification of bodies found in clandestine graves.