Aside from corresponding declines in prices of its component instruments, the dip in HBA for December was affected by "limitations of import quotas by the China government," the ministry said in a statement.

The HBA is a monthly average of the Argus-Indonesia Coal Index (ICI-1), the Platts Kalimantan 5,900 assessment, the Newcastle Export Index and the globalCOAL Newcastle index from the previous month.