Mexican security forces have discovered another 17 bodies from mass graves found last month in the northern state of Durango.

The discovery brings the number of bodies recently unearthed in Durango to 218. That total eclipses the 183 bodies found in pits last month in Tamaulipas.

Durango’s security agency said on Saturday that the excavation also turned up a bag of bones.

State investigators have not speculated on a motive for the killings, but drug cartels have been blamed for mass graves found in other states.

The Sinaloa, Zetas and Beltran Leyva cartels have been fighting for control in Durango.

Copyright 2011 The Associated Press.