The bodies of 31 people have been exhumed from a mass grave in the Mexican state of Veracruz, a military official said.

The bodies of 24 men and seven women were found on Monday at an abandoned ranch by members of an army patrol.

Eleven of the bodies had been decapitated, several were missing hands or feet and investigators also found ears and fingers, according to a state police official who oversaw the exhumations.

The motive for the killings is not known.

Some of the victims had been in the grave for more than a month, prosecutor Arturo Herrera said.

Veracruz is a stronghold of the Zetas, one of Mexico's most dangerous cartels.

There have been numerous mass graves found all across Mexico since the government in 2006 launched a military offensive against drug cartels.

After President Enrique Pena Nieto took office in December 2012, the government said it had a database of 26,000 missing people. However, it has since said that that figure might be revised downwards.

The government says another 80,000 people have been killed in drug-related violence in Mexico since 2006.