Deadly clashes between troops and armed cattle rustlers on the Indian Ocean island of Madagascar have left 23 people dead, the army said on Thursday.

Eight of the dead were soldiers while 15 of them were cattle thieves, known as "dahalos" in the local Malagasy language.

"We have eight soldiers killed and another 12 injured," said Theophile Rakotonirina, head of the army's operations and intelligence unit.

"We have also identified 15 dead dahalos."

The incident took place early on Wednesday in an area near Ankazoabo in southwestern Madagascar. Troops were alerted to the theft by a cattle breeder who had 90 of his zebu stolen.

Hunting the prized humped zebu cattle is a rural tradition among young Malagasy men who do it to prove their virility and valour.

A symbol of wealth, zebu are at the heart of local culture in southern Madagascar, where they are eaten only at weddings or special celebrations, sacrificed for ancestor worship or in burial rituals.

The tradition of stealing them has fuelled inter-communal violence, with the army accused of carrying out extra-judicial killings and razing villages that are suspected of sheltering cattle rustlers.