The Special Monitoring Mission of the Organization for Security and Cooperation in Europe (OSCE SMM) has said it observed militants of the self-proclaimed Donetsk People's Republic (DPR) using multiple-launch rocket systems during the latest upsurge in tensions around the city of Donetsk on June 3.

"From the Joint Center for Control and Coordination (JCCC) observation point at the Donetsk central railway station [DPR-controlled, 8km north-west of Donetsk city center], over a nine-hour period during the day, the SMM heard 249 explosions of both incoming and outgoing fire consistent with artillery, mortar and multiple-launch rocket systems [MLRS] outgoing from south, west, north-west, north and north-east of the SMM position. Most of the MLRS shelling originated from the DPR-controlled Kyivskyi district [8km north-west of Donetsk city center] and Spartak [8km north of Donetsk]," the mission said in its report.

"It was mostly concentrated and impacted in the area of government-controlled Opytne [10km north-west of Donetsk]," it said.

"The SMM observed civilian infrastructure on fire 500m south-west of Donetsk airport," the mission said.

"In the DPR-controlled areas the SMM observed 12 main battle tanks [MBT T-64 and T-72] and a military-type truck towing a 122mm artillery piece. In government-controlled areas the SMM observed a single MBT [T-64]. Additionally, the SMM UAV [unmanned aerial vehicle] observed four MBTs and three howitzers in government-controlled areas," it said.