The dismembered bodies of nine men have been discovered in an abandoned truck in south-west Mexico, police say.

The body parts filled 18 bags and were found on an isolated road in Guerrero state with a message from the drugs cartel La Familia, officials said.

Some of the victims were shot before being beheaded, state police said.

Analysts say Guerrero has seen an upsurge in violence between La Familia and other cartels for control of important drug smuggling routes.

The gruesome discovery was made in the back of a truck that was blocking a highway in the town of Tlapehuala, AP news agency reported.

"La Familia doesn't kill innocent people - those who die deserve to die," the hand-written message said, according to another report.

La Familia is based in the neighbouring state of Michoacan, the home state of Mexican President Felipe Calderon, and has a reputation for extreme violence.

Mr Calderon has deployed more than 45,000 troops to fight drug gangs since he took office in December 2006.

However, more than 11,000 people have been killed in drug-related violence in that time.