Police in a Mexico City suburb have arrested a mother and several relatives for allegedly gouging out the eyes of her five-year-old son in what authorities said was a drug-fuelled ritual.

The boy was taken to a hospital in Nezahualcoyotl, a part of Mexico state bordering Mexico City, in a serious condition yesterday and later transferred by helicopter to a more specialised facility in the capital.

Nezahualcoyotl spokesman Fernando Chavez said a passing police car was flagged down by someone who reported the incident. When officers entered the home they found the mother in shock with the boy in her arms.

"Once the woman allowed local police to check the boy, they were astonished to see the boy had no eyeballs," he said.

Mexico state prosecutor Isaac Acevedo said a total of eight people had been detained and that investigators believed the mothergouged the boy's eyes out with her fingers. The boy's father was apparently not in the home at the time.

The crime appeared to have been part of a ritual, but was not apparently related to the Santa Muerte or Saint Death cult, some of whose followers were recently charged with the sacrificial killings of two 10-year-old boys and a 55-year-old woman in northern Sonora state, he said.

The boy's aunt and uncle were also apparently at the house when the adults began using some unspecified drug.

Mr Chavez said one witness told police she had passed out under the influence of drugs and when she regained consciousness, the boy's eyes were gone.

The adults have not yet been charged in the case, but are being held pending investigation. Two children and a 17-year-old were also found at the residence.

In March, authorities in Sonora state arrested eight people for allegedly sacrificing the two boys and adult woman as offerings to Saint Death, an idol usually depicted as a robed skeleton. Followers of the cult include criminals and drug traffickers.

While statues of Saint Death are common in many poor Mexican neighbourhoods, Mr Chavez said no altar or statue of the figure was found in the Nezahualcoyotl home.

Mexico's worst case of ritual sacrifice came with the notorious "narco-satanicos" killings of the 1980s. Fifteen bodies, many of them with signs of ritual sacrifice, were unearthed at a ranch outside the border city of Matamoros, across from Brownsville, Texas.