MINSK, Belarus (AP) — Five people have been detained and one policeman injured in a clash between Ukrainian nationalist demonstrators and police outside the presidential administration building in Kiev.

The Sunday evening clash involved demonstrators in camouflage and balaclavas who tried to set up a tent camp in support of nationalists who have blocked coal shipments from parts of eastern Ukraine held by Russia-backed separatists. The blockade has led to power shortages in government-held parts of Ukraine.

Police said those detained included Nikolai Kokhanivsky, leader of the Organization of Ukrainian Nationalists.

Ukrainian forces have been fighting separatist rebels in the east since April 2014, a conflict that had killed more than 9,800.