Separatist leaders in eastern Ukraine are threatening to abandon a cease-fire following changes to a law granting their regions self-rule.

Alexander Zakharchenko and Igor Plotnitsky said Wednesday in a statement that legislation giving areas of the Donetsk and Luhansk regions special status has been weakened by the amendments.

The leaders say they are willing to resume hostilities unless Ukraine relents.

A law on granting autonomy to eastern territories was approved by parliament Tuesday. Foremost among the rebels' objections is a requirement for elections — to be held under Ukrainian laws — to take place before the special status can come into effect.

More than 6,000 people have been killed since fighting broke out last April. Clashes have reduced substantially since a cease-fire was declared last month.