Gruesome find in Mexico City

Some of the skulls found by Mexican police

Police patrolling near one of the main tourist areas of Mexico City have discovered caves lined with human and animal remains - including at least 20 human skulls.

Reports say the skulls were surrounded by dissected animals hanging from the cave walls.

The government news agency Notimex said police found the cave after two men opened fire on a patrol car and officers chased one of the men into one of four adjacent caves.

Forensic experts say the skulls are at least 10 years old. One of the skulls bore the words "health," "money" and "love" written in red ink. A devil was painted on one side of the cave. Some have what appear to be bullet holes.

Puzzle for police

It is a mystery what purpose they had served and why they had been collected there.

According to police, the arrested man told them that he and his friends used the caves to rape women and that four women's bodies were buried in a nearby cave.

The one-metre high cave is located on a dusty hillside in Mexico City's Chapultepec Park, home to some of Mexico's most prestigious museums.

Nearby is a concrete wall marking the edge of a major cemetery.