PRISTINA, Kosovo (AP) — Kosovo's prime minister is complaining that Serbia is using "pressure and blackmail" to persuade ethnic Serbs to resign from the security forces.

Ramush Haradinaj on Thursday said that due to Belgrade's "attacks and blackmail on Serb members of the Kosovo Security Forces (FSK) they have resigned from service," without specifying how many had left.

The FSK, the nation's security forces, needs a constitutional mandate to turn into a regular army, but that cannot be passed without the ethnic Serb minority's approval.

Kosovo declared independence against Belgrade's wishes in 2008. Nine years earlier, NATO had intervened to stop a bloody Serb crackdown against Kosovo Albanian separatists.

Haradinaj said he considers Belgrade's pressure "meaningless" and "unfair."

Despite seven-year EU-facilitated negotiations between Pristina and Belgrade, the friction between them remains high.